Patch 1 addresses the following problems:
 - configuration. Hope there are no silly problems left..
 - inode.c: initialization changes (the missing NULL and some other
   minor fixes).
 - some SCSI tape driver patches (Kai M{kisara)
 - tcp/ip patches (Ross Biro, some code by me)
 - keyboard patches (mainly changed initialization - hope the keyboard
   lockups are gone).
 - completed /proc-fs: it should now contain all info needed by 'ps'
   (Micheal K Johnson).
 - various minor fixes (the minix-fs link overflow checking etc)

Patch1 also contains support for extended VC switching - this is for the
upcoming X11 that understands VC's.  One result of this is that console
redirection now redirects *only* messages actually sent to /dev/console
(aka /dev/tty0), not just to any foreground VC.  Wait for Xfree-1.2 to
be able to switch VC's while under X (yes, including several X-sessions
active at the same time..).

I hope there are still people out there that aren't too busy stuffing
themself with turkey to try out a new kernel release.  There is just
over a week left of this year, and I need feedback in order to be able
to release 1.0.

                Linus

PS.  Thanks to everybody who has sent me Christmas/New Year/Birthday
cards.  Some contained money, some didn't, and I enjoyed them all.
Thanks.

net-1: paranoid queue checking to find more bugs.

configuration script version #1.

NFS filesystem client support by Rick Sladkey!

[Original announcement below]

0.99 has no major new features: the NFS client code is now in the
standard distribution, and the kernel configuration has changed, but
most of the rest of the changes are fixes - especially the tcp code
should now be pretty stable (knock wood).

Changes:

 - NFS is in. As are some stubs for the soud drivers, although it's only
   stubs right now.
 - various fixes around the place: the serial problems are hopefully
   gone, and there are patches to both TCP/IP and SCSI to make them more
   stable.
 - Minor fixes: the keyboard buglet introduced in 0.98pl6 should be
   gone, and some other bugs are also corrected.  The optimized
   read-ahead code in the filesystems (and the raw device read code) was
   too complicated and seemed to have problems with bad blocks, so I
   rewrote it, and it should hopefully work correctly now (this may have
   been the reason "mkfs -c" didn't work in all cases).  Thanks for some
   good bug-reports I've gotten: I've tried to correct all the problems
   I got reports on.
 - The kernel configuration has been re-thought: I decided to take
   advantage of the possibilities offered by GNU make etc.  This means
   that you no longer can compile the kernel using any other make, but
   there probably aren't many (if any) people doing that anyway.  This
   way I got rid of the extremely ugly SCSI setup, so it was probably
   worth it.

To configure the kernel for your setup, do a

        make config

and answer the yes/no questions. After that, do a

        make dep

to make the dependencies match your setup.  After that you should still
go edit the top-level Makefile for some of the configuration information
as before, but the remaining config things are pretty simple.  Then you
can make the kernel with a simple "make Image".

The new configuration utility (essentially a stupid shell script coupled
with some smarts in the Makefiles) tries to minimize compilations: if
you disable the SCSI code the scsi drivers won't even be compiled, much
less linked in.  This should be a win on slower machines.

NOTE!!! Use LILO-0.7 to load the 0.98pl5 and newer kernels: any older
version of lilo is liable to result in weird problems.

                Linus

Kai Makisara does the SCSI tape driver.  He's one of the few original
maintainers still around as such..

isofs introduced by Eric Youngdale, based on the minixfs code.  Eric was
a physicist, and you can tell he was new to C - he has been
Pascal-damaged, and has extra semi-colons at the end of block
statements.  But soon he ended up being one of the core maintainers
anyway, and took over SCSI maintenance.

More aggressive filesystem read-ahead introduced.

[Original announcement below]

Anyway, 0.98pl6 is hopefully the last release before 0.99: there are a
few known problems left in this release.  Most notable is the serial
code: it works for most people, but others still have problems with it.
I hope this will get fixed within a week (tytso is working on it).  It
also seems as if the PS/2 mouse code has some problems.

pl6 contains these fixes:

 - all the tcp/ip patches I've received (and I fixed one bug that
   gcc-2.3 seems to have found).
 - math-emu patch for the problem that resulted in FPU errors with some
   operations.
 - I fixed gcc-2.3 warnings as well as most of the old warnings.  You
   shouldn't get more than one or two warnings when recompiling the
   whole kernel.
 - /proc filesystem extensions.  Based on ideas (and some code) by
   Darren Senn, but mostly written by yours truly.  More about that
   later.
 - some tty_io fixes (there was a bug in the /dev/console handling when
   you changed VC's while using the general console device).
 - re-organization of the keyboard-driver internal data-structures.  The
   changes are mostly preliminary: they change the keyboard flags to be
   more easily adaptive to a reprogrammable keyboard driver.  No actual
   new features yet.
 - new SCSI drivers: reportedly much faster than the old ones (but not
   all drivers take advantage of it yet..)
 - various other fixes: pty's etc have minor changes.

I hope to make 0.99 in a week or so, and 1.0 after that has been tested
some.  I hope people will test out pl6 - 0.99 won't be much different,
and if you don't test pl6, any bugs relating to your particular hardware
may not be found in time for 0.99...

                Linus

net-1: free_skb -> kfree_skb. More changelogs.

[Original announcement below]

0.98.5 mainly fixes the swap-partition bug that was present in pl4 (and
for which I did an earlier unofficial emergency patch).  The bug
resulted in incorrect swapping with a partition under some circumstances
(notably tty events: keypresses could make xterm dump code when swapping
was enabled etc).

pl5 also has some other changes - nothing major.  Setting and querying
termios information from a pty master will now set/query the slave info:
this seems to be what some programs (telnet) expect.  I haven't seen any
changes to any of the programs I use, but I'd like to hear if this
results in problems or if it actually does help.

NOTE! READ THIS AND PONDER:

pl5 now checks against writing to the text segment.  Older binaries
which used the original estdio library (used with the earliest gcc
versions) are liable to break: not that there should be many of these
binaries around.  So if you get "Segmentation fault (core dumped)" on
binaries you know used to work, this is the likely cause.

One problem spot that I've seen even with new binaries is due to a
library bug in 'sigaction()'.  If the second argument is NULL (ie the
pointer to the new sigaction structure), sigaction() will incorrectly
dereference it resulting in a core-dump.  The only program so far that
I've seen doing this is 'dd', but there may be others.

On my system I have found a whopping total of two binaries which didn't
like the text segment protection, so it shouldn't really be a major
problem for anybody.  Famous last words.

                Linus

PS. The strace code in pl4 was incorrectly credited in the announcement.
The code was written by Branko Lankester, not Ross Biro (who did the
tcp/ip changes).

Rename "malloc()/free()" as "kmalloc()/kfree()" to make people more
aware of some of the limitations.

Math emulator updates to handle the case that Linux (unlike the original
djgpp target) can get preempted by user space accesses.

Make "ll_rw_blk()" take an array of blocks to read/write.

VFS "notify_change()" callback, to allow the low-level filesystem to
decide what it wants to do about metadata changes.

Deprecate old "stat()" call by printing out a warning on use.

NR_OPEN is now 256 files per process, and the old "unsigned long" bitops
needed to go away. This causes lots of syntactic changes in select().

System call tracing implemented for ptrace().

[Original announcement below]

 - the inode caching bug (resulting in bad filesystem info when
   mounting/umounting devices) should be gone for good.

 - an elusive race-condition in the fs is fixed: this may have been the
   reason some people got fsck errors once in a while.  The
   race-condition was pretty hard to find, and depends on a lot of
   things (buffer cache size, speed of the disk and computer speed).

 - fpu emulator patches (mainly for the re-entrancy problem) by me and
   W. Metzenthen.

 - various wait-queue changes - the kernel uses the waiting mechanism
   more efficiently now.

 - the NFS client support code is there: the actual nfs code is still in
   alpha (although reported to be pretty stable) and has to be gotten
   separately.

 - NR_OPEN was changed from 32 to 256 (which is what SunOS seems to use,
   so I hope it won't need any further changes).  This has lead to some
   incompatibilities (GNU emacs and the term program seem to need
   recompilation to work correctly), as the 'select()' system call has a
   slightly changed interface due to the new fd_set definition.

 - the process kernel stack is now on a separate page (needed due to the
   fact that the task_struct has now grown to almost 3kB due to the
   NR_OPEN changes).  This also means 'ps' needs patches..  My patches
   to ps-0.98 are available as 'ps-diff.Z' in the same directory as the
   kernel sources and diffs.

 - various other changes: system call tracing by Ross Biro. Changed
   ll_rw_block interface (performance reasons: it will eventually be
   changed to accept several requests at once).  Malloc() was changed
   and renamed to kmalloc() due to the new interface.  Some tcp/ip
   patches (inode counting correction and some other changes).

0.98.4 should hopefully be pretty stable: the main problem areas are
probably still tcp/ip and some of the tty code.  I'd appreciate
comments, bug-reports etc.

                Linus

More networking updates.. Ross Biro is still struggling with net-1.

Michael Johnson (now RH kernel release manager) works on line printer
driver.

Locking function cleanups (for inodes, superblocks, buffer heads).  We
also now pass in the superblock pointer instead of the device number to
the filesystem routines.  That cleans up use and locking of
"get_super()" a lot.

[Original announcement below]

Ok, I already sent out an announcement last night, but due to the time
(6AM over here) I wasn't really in a mood to write a real annoucement.
Here it is.

linux-0.98.3 is available by anonymous ftp at least on nic.funet.fi:
pub/OS/Linux/testing/Linus, both as context diffs against 0.98.2 and the
pre-version of 0.98.3 and as complete source. The complete source
package was done by directly applying the diffs - this means that the
Makefile dependancies are probably not 100% up-to-date as I remove those
from the diffs. It shouldn't be any problem, and you can always do a
"make dep ; make clean" before actually compiling the kernel.

0.98 pl3 fixes several bugs, and should remove all known NULL-pointer
problems that made 0.98.2 unusable for most people. In addition to the
NULL pointer fixes, the following things have changed:

- removed most of the cli-sti pairs in the filesystem code by rewriting
  the locking routines to use a different algorithm, possible due to
  the rewritten wait-queue code that I did back in 0.96c or so.
  Interrupt latency should be better on slow machines, but I don't know
  if it's noticeable.
- Minor 387-emulation fixes by Bill Metzenthen - only noticeable under
  special conditions.
- Corrected various error-returns in the fs (thanks to Bruce Evans for
  running some error diagnostics). Error messages when opening (and
  renaming etc) files that had a non-directory in the path were wrong,
  and should be ok now (ie giving ENOTDIR instead of EACCESS or ENOENT).
  Some other problems reported by Bruce fixed.
- Changed the interface for some fs-related functions due to cleaning
  up super-block handling. Most noticeably, iget() and related
  functions no longer specify the inode with a device and inode number,
  but instead with a super-block pointer and inode number. This is
  more logical, and should make unnamed devices (ie internal
  filesystems like nfs and /proc) cleaner. Also note that the calling
  sequence for sb->s_op->put_inode() also has changed since 0.98. This
  is of interest only if you are writing filesystem drivers..
- ASK_SVGA was broken in 0.98.2 - it should be ok now.

Also, various minor fixes as usual. No new features, but I hope 0.98.3
will be a lot less bug-prone due to the changes since 0.98.1. Some
minor tcp/ip corrections (but most of them were in the pre-release), and
I removed a race-condition in the tty-handling code.

Note that people who use math without a co-processor should certainly
upgrade to 0.98.3: the new emulator is much better than my original one
both in speed and accuracy/exception handling. x11perf is very much
bearable now even without a 387, and things like ray-tracing etc
shouldn't be a problem any more. It's slower than hardware fp, of
course, but at least it works.

The new emulator also means there is no reason for a separate soft-float
library, so I'd assume that will be gone in the next gcc release for
linux.

As usual, a new kernel version probably means you'll have to recompile
'ps' and friends. But at least the same 'ps' sources that worked for
0.97.6 should still work.

                Linus

Start virtualizing real mmap() functionlity in the kernel.  The first
signs of me thinking about this already showed up as some unused header
files earlier, this fleshes things out some more.  No actual filesystem
code yet..

This also removes my old simple math emulator, and introduces the new
and much improved one from Bill Metzenthen.

Bill originally wrote it for the djgpp suite (DJ Delories gcc port to
DOS extenders).  It was much more accurate and well designed than my
hackish one, and I was happy to throw my old code away.  The new math
emulator also did things that I had never bothered with, notably the
more complex i387 functions (exponentials and trig).

I also fixed the static maximum memory limit: we now generate the kernel
page tables dynamically rather than having a 16M or 32M static limit.

SCSI updates: removable media support (which also implies re-reading the
partition table etc)

[Original announcement below]

patch-2 is >150kB compressed, as it contains several big changes. Most
notable are:

 - the new FPU-emulator by Bill Metzenthen.  It's bigger than the old
   one, but thanks to it, linux fpu emulation is no longer a quick hack,
   but a real emulator: it does all the 387(486) math instructions, and
   does them much faster than the old emulator + the soft library.

   The new math-emulator means that a separate soft-float library is no
   longer needed.  It also makes even a non-coprocessor system pretty
   useful for limited math-calcs - the complex functions are much faster
   when they no longer have to be calculated using simple functions, and
   even the simpler instructions that my old emulator handled are faster
   using the new one.

   The size of the new emulator may mean that people who have little
   RAM, but do have a coprocessor should probably recompile the kernel
   with the emulator disabled.

 - various minor mm fixes by me: trapping kernel NULL dereferences,
   cleaning up the page table initializations and the 16MB patches, and
   various other bugfixes.  get_free_page(GFP_ATOMIC) should preserve
   the interrupt flag, so malloc() should be safe now - hopefully no
   more of the tcp/ip memory management problems.

   The NULL pointer trapping may result in errors like:
        Unable to handle kernel paging request at address C0000???
        Oops: 0000
        ..... debugging info .....

   There were several NULL pointer dereferences in the serial and tty
   drivers, which should now be fixed.  I've also fixed any other errors
   I've seen, but if there are problems in the scsi drivers or similar
   things I cannot test, I'd like to hear about them.

 - scsi driver changes by Eric Youngdale.  Preliminary support for
   removable media, and some bug-fixes.  Due to white-space problems
   with eric's patches, the scsi patches are a bit bigger than
   necessary, but they should be ok even though I had to put them in
   partly by hand (and being unable to test them...)

 - The new tcp/ip patches that were sent to the NET channel not long
   ago.  Yes, they are alpha, but so is the whole tcp/ip directory, so I
   put them in even thought they haven't been extensively tested (and
   they did have a serious problem in the ioctl code, which I fixed).

 - psaux mouse patches by Dean Troyer, as well as the mouse.wait = NULL
   patch.

Before (or after) patching, you should remove the old math-emulator (ie
"rm -rf /usr/src/linux/kernel/math") as it is no longer needed.  You
should also do a "make dep" to update dependencies: as usual, I edited
out the dependancy-changes.  Do a "make clean", edit the main (and net)
Makefiles to suit your system, and compile.

And finally: I will no longer be making the bootdisks available -
they'll be made by hlu/jwinstead and will probably be boot+root-disks
using lilo, as done on the hlu disks.  That may mean that a bootimage
won't be available at once, but most people who want to use the
absolutely newest images probably compile them themselves anyway, so
that shouldn't be a problem.

                Linus

Add ATI XL busmouse driver by Bob Harris, split off MS busmouse driver into
a driver of its own (rather than a subdriver of the Logitech mouse driver)

FAT uid/gid/umask mount options.

SCSI driver updates.

[Original announcement below]

Patch1 to 0.98 mainly corrects some driver problems: it contains the
added "inb_p(HD_STATUS)" for hd.c, as well as a changed mouse driver
setup (hope it works - I couldn't test it..).  There are also some SCSI
driver patches: the seagate driver uses irqaction() to get irq's, and
the aha1542 driver has the speedup patches.

The bootimage should be compiled without the auto-SVGA mode, so people
who had problems with linux automatically using a SVGA mode should be ok
in this release.

                Linus

Real networking (TCP) merged! This is the now-called "net-1" code by
Ross Biro.  Boy, was it ugly, but it made for a big jump from not having
any at all.

(And add support for up the 32MB of memory ;)

[Original announcement below]

Sorry for being late - I can't even show any great new features in 0.98,
but at least it's out now, and available at the normal place (ie at
nic.funet.fi, pub/OS/Linux/testing/Linus).  So far there is only a
full-source version available, although I'll probably make it available
as a patch too tomorrow or so (but the patch won't contain the tcp/ip
stuff).

0.98 is essentially the same as 0.97.pl6 - the changes are mostly:
 - tcp/ip (0.8.1) is in.  It's not compiled into the standard bootimage,
   and you'd better be on the tcpip mailing-list to use it, but it's
   there. I've been unable to test it further than just watch it
   compile...
 - extfs patch to correct the problem with big directories with holes.
 - mouse patches (ie improved detection-routines)
 - minor scsi patches (ultrastor driver change)
 - swiss keyboard
 - some serial driver patches
 - the 32mb patches are in, so if you aren't using a DMA-SCSI driver,
   and have more than 16MB physical memory, you can get it recognized.
 - edited hd.c
 - corrected core-dumping routines

I didn't get my mm patches working yet, so they'll have to wait.  The
above are almost 100% by others - I have edited some of the patches, but
there is nothing major new by me.  Most of it is minor bug-fixes, and
the only thing that might be a bit of a problem are the hd.c changes:
but I hope they'll solve more problems than they cause.  Knock wood.

At nic.funet.fi you can currently find (a) the full sources (b) a
bootimage (US keyboard, floppy root, no tcp/ip) and (c) the protocols.h
file needed for compiling the tcp/ip directory (which should go into
/usr/include/netinet/).  I hope people try it out, and that there are no
new problems with this release.

                Linus

Ted Ts'o did extensive serial driver changes, and fixed up some of the
tty layer to match.  Tty's now allocated dynamically.

[Original announcement below]

This patch does not contain any major bug-fixes: it corrects named pipes
that broke with pl5, and has some minor changes in the IO-instructions
and the hd-driver, but those shouldn't matter for most of you.

It does contain all the scsi-patches that I've gotten so far, so if the
bootup sequence died on you in the scsi code, pl6 should correct this.

The major part of the patch is tytso's serial line changes, making the
tty structures dynamic.  No more NR_PTY's - the number of pty's is now
bounded only by the minor number setup (max 64 pty's) or the amount of
memory available (opening a pty requires a page of memory for tty
queues).  Similarly for serial lines.

The above just means that while pl6 can be useful, the changes to pl5
aren't big enough to worry about.  Most people don't use named pipes, it
seems, and the other changes are either cosmetic or hardware-dependent.
I still hope people upgrade, if only so that I can get new bug-reports.

I had hoped to release 0.98 this weekend, but studies and the scsi/hd
problems put an end to that.  0.98 should be out next weekend or so.
Expect the tcp/ip subdirectory and possibly some mm changes.

                Linus

SCSI CD-ROM support by David Giller (based on sd.c by Drew)

Microsoft Busmouse support by Teemu Rantanen

Do the same buffer cleanups to extfs that we just did to Minixfs.

Efficient VGA emulation in dosemu wanted to know when we write
to the pseudo-VGA memory area. Add vm86 mode hooks for that.

[Original announcement below]

Patch 5 fixes the extended filesystem problems (thanks to Remy Card), as
well as including many smaller fixes (some more fs cleanups, the CDROM
patches and several other minor changes).  Pl5 finally removes even the
last few header-files that were incompatible with the normal headers, so
the "-nostdinc -I$(KERNELHDRS)" stuff is gone.

Patch 5 should also fix the problems with iopl() that resulted in the
X8514-server having problems with 0.97.pl2 and above.

In case people are wondering, my schedule for 1.0 looks something like
this:

 - 0.98 out in about a week: this is essentially 0.97.5 + the tcp/ip
   directory, as well as any fixes that may come up.  I'll try to get
   the loadable driver interface into it too.

 - 0.99 out after 0.98 has been shaken down: a month or so.

 - 1.0 will be the same as 0.99: the only changes will be eventual
   trivial bug-fixes in case 0.99 has some problems.  This is just to
   try to get over the "X.0" bug syndrome.

There are a few on-going projects: depending on circumstances these will
be implemented sooner or later, so I won't give any promises.  These
include: loadable drivers/fs's (alpha-patches already availabla), full
support for different block-sizes (some work still required), and a
extensive rewrite of the mm routines (I'll want to make a vmm interface
similar to the vfs interface for the filesystem routines).

                Linus

Linus "dances with patches" Torvalds strikes again: I've already made
patchlevel 4 of 0.97.  It may not be a new record, but it's close :-)

Patch 4 is a very minor patch, but it's pretty important if you want a
stable filesystem (and let's face it: most people seem to prefer a
filesystem that stays up a bit longer).  While patch3 corrected most of
the race-conditions in the minix fs, I overlooked the [f]truncate system
calls, and this new patch corrects that.

[f]truncate is a very race-prone function, and as if that wasn't enough,
there was also a pretty bad error in truncate.c that resulted in the
indirect blocks not being correctly marked dirty when doing partial
truncates.  The latter problem is probably the reason for most of the
filesystem corruptions that have been reported - the race-conditions
were a lot harder to fix, but they also happen a lot less often.

Note that the [f]truncate bug isn't new: it has been in the kernel since
[f]truncate was first implemented (0.95?).  But until now, [f]truncate()
hasn't actually been used very much - only the latest versions of the
binutils have used ftruncate to strip binaries etc.  So the problem
hasn't shown up that much.

So while I consider patch4 to be crucial, you /can/ actually live
without it: I haven't seen the buffer corruption problem at all (until I
actually tested for it after getting good bug-reports), so you can
provably miss it for a long time.  But if you have ever had corruption
problems, I'd suggest upgrading to pl4 as soon as possible.

The corruption problems show up most clearly when using a new "strip"
binary, although they are theoretically possible with other programs
too.  Thanks to "obz@raster.kodak.com" and "jon@robots.ox.ac.uk" for
good bug-reports: thanks to them I was able to pin down the error to
truncate.c, and after that it was pretty easy to get rid of it.

Also note that this patch still hasn't fixed the extended filesystem: I
suspect the same bugs lurk around there.  I'll get it corrected by 0.98
at the latest.

The patch is included at the end of this post (it's very minor - it
contains patches mainly against linux/fs/minix/truncate.c) , and I'll
also update nic.funet.fi (pub/OS/Linux/testing/Linus) to have the new
sources.  Sorry for the inconvenience,

                Linus

Hey, we switched to the GPL several months ago, but only now do we
include the license text itself.  Apparently everybody expected
everybody else to just know what the GPL was..

Add a README on compiling the kernel (by Lasu)

Add PS/2 mouse driver, make generic "mouse" infrastructure.

Add /proc filesystem, clean up minixfs block mapping.

sys_wait4() and swapoff().

VM gets a "secondary page free" list for things like interrupts
that want a page _now_ and can't wait for the regular free list
to fill up.

[Original announcement below]

Patch3 is almost 100kB even compressed, as there were quite big changes
in the mm and minix fs.  No major new features: there are two new system
calls: swapoff(const char * swapfile) and wait4(), and linux accepts
several swap-files, but the rest of the thing is mostly bug-fixes or
simply rewrites.

Major changes:
 - new swap-page handling: linux no longer uses just one bit to keep
   track of used swap-space, but a counter for each swap-page.  This
   allows processes to share swap-pages after a fork(), and should
   result in /major/ performance increases on machines with less memory.
   I've seen better performance even with 8MB - I wouldn't be surprised
   if 4MB machines would re-compile the kernel noticeably faster under
   pl3.  I'd be interested to hear numbers.
 - The low 1MB memory that isn't used directly by the kernel is now
   swappable memory, instead of being hardcoded for buffer cache.  The
   patches for this were originally by tytso, and I expanded on it a bit
   more.  This might also help better performance on 2-4MB machines.
   Note that this does /not/ mean that you can use 1M machines for
   linux: linux still needs some extended memory.
 - the dosfs has been upgraded to dosfs.8 - patches by almesber.
 - I edited the minix fs pretty heavily to remove a couple of race-
   conditions.  The same races still exist in the extended fs, as I
   didn't have time to edit that yet.  The minix-fs took precedence as I
   know that better, and extfs isn't "official" yet anyway.

other changes:

 - the mouse-driver now handles both Logitech (minor = 0) and PS/2
   (minor = 1) busmice.
 - there is a proc-fs for access to user memory/files etc.
 - better support for the tcp/ip patches (but see below...)
 - corrected symlink and /dev/[k]mem behaviour
 - Lars Wirzenius' README (with minimal comments by me) and the GNU
   COPYING notice are now part of the normal kernel setup, and can be
   found in the tar-archive.
 - the floppy ioctl() to get the FD parameters no longer requires root
   priviledges.  Thus, the msdos emulator runs even for a normal user.

Some comments on patchlevel 3:

        mm:

The swap-page handling resulted in a reduction of swap-file (or
partition) size to a maximum of 16MB per file.  It's nothing inherent to
the code, but it eased some algorithms, so I didn't bother coding around
it.  After all, 16MB is enough for most people, and if you want more,
you can have up to 128 swapfiles of 16MB each.  If I get enough
hate-mail about it, I might just try to find the energy to correct it.
Maybe.

Bigger swapfiles will still work, but linux will take advantage of only
the low 16MB.  Also, there is no nifty logic to try to optimize the
usage of the swap-files: pages are simply allocated from one swap-file
until it fills up, and then the next swap-file is used.

The memory management changes break ps/free once more, but not very
much.  Also, I changed the load-average counting, so 'w' also needs
slight editing.  On the other hand, I made '/dev/kmem' mmap()able, and
'ps' and 'free' should be edited to take advantage of that: it should
result in much faster operation, as well as possibly using less real
memory.

        fs:

The fs changes should remove at least two races - the races don't happen
very often, but they were theoretically possible, and might be the
reason for some fs corruption problems that have been reported.  The
changes are related to the use of bmap() - the bmap interface doesn't
really lend itself to some things that it was used for.  Re-writing
internal fs-functions not to use bmap not only should have removed any
races, but also actually resulted in cleaner code.

The proc-fs code isn't too beautiful, and I'll probably leave it out
from 0.98 unless I can make it loadable.  We'll see.  If anybody wants
to use it, you can do something like

  # mount -t proc /dev/ram /proc

Instead of /dev/ram you can use any block device - it's not used, and is
only a dummy as the proc-fs doesn't actually use any external device.
(but note that the device is still marked as mounted, so you cannot
mount it for anything else).

        kernel/mm/lib:

The TCP/IP patches are also essentially in 0.97.pl3 - not the full
TCP/IP directory, only the patches to the main kernel.  NOTE!! I don't
like the 'grab_malloc_pages()' function, so I left that out, and added a
GFP_ATOMIC priority to get_free_page() that should be used instead.  I
hope this will be used (Ross?), as it's a lot cleaner.

Also, I hope the tcp/ip people will clean up malloc() so that it doesn't
panic instead of returning NULL etc.  Ugly, ugly.  This is related to
the get_free_page(GFP_ATOMIC) changes, and I'd like to have patches as
soon as possible - tcp/ip won't be part of the standard kernel until
that can be cleaned up.

                Linus

We're making ready for big processes, and vm86 mode!
 - Move the kernel to virtual address 0xc0000000 instead of zero.
 - Allocate per-process page tables

We can now have 3GB processes, and more than 64 of them!

[Original announcement below]

As promised, 0.97.pl2 is out today (well, over here it's already
tomorrow, so I guess I'm 35 minutes late.  Naughty, naughty).  Right
now, the patch (and full source for those that don't like to patch up
the system) is available at "nic.funet.fi: pub/OS/Linux/testing/Linus",
but I'll try to put it on some other sites as well if I'm able and
energetic enough.  Probably tomorrow - together with a binary for those
that aren't willing to comple the kernel on their own.

0.97.2 has mostly my mm/fs patches, along with some relatively minor
diffs by others (including file locking by Doug Evans).  User-level
changes are minor: but the mm has changed a lot, and the vfs routines
have been changed to keep track of the error-messages a bit better.
Also, the vfs-interface to "follow_link()" changed slightly: people who
are making filesystems should look at the changes (but they are
relatively minor, and shouldn't result in any problems - both the
extended fs and minix fs needed just a simple change in their respective
symlink.c files).

The mm changes /might/ lower performance slightly, as the paging TLB's
are now flushed at every task-switch due to the new system, but I doubt
it's noticeable.  The other performance changes (dynamic buffers etc) in
0.97(.pl1) should overshadow that particular problem.

I hope this release means that these kinds of low-level rewrites aren't
needed for a while: the last couple of releases have changed some very
fundamental things.  Nothing seems to have suffered too badly, but I'd
be happier if it all got tested more thoroughly.  Anyway, discounting
the ps/free etc suite of programs, everything I have tried has worked
flawlessly despite the big kernel changes.

I'm still worried about the reports about messed-up buffers, but have
been unable to reproduce the problem, and nobody has so far
disillusioned me about my guess that it's a problem with the SCSI code
(which at least gives me an excuse for not doing anything about it :-).
Other problems include at least one report of spontaneous re-booting,
which is totally inexplicable, so I'm blaming hardware once more until I
can get better data on the thing.

As to patches sent by others: 0.97.2 contains very little of that kind
of code.  I've been too busy either working, or implementing my own
changes that I have simply ignored them for the most part.  Remind me
(or resend them relative to the new kernel) if you have a patch that is
still needed.

There is one new system call: 'vm86(struct vm86_struct * info)'.  It's
not ready for general use yet - it works, but will probably need some
tweaking before being practical.  But supporting a virtual 86 mode was
so easy after the mm rewrite that I felt it was worth implementing: the
vm86 code is less than 50 lines of C right now.

                Linus

PS.  The bright spot of the week goes to "The Oxford Beer Trolls" - all
UK inhabitants should probably be locked into some (big) mental
institution and TOBT should probably have a wing of their own, but
thanks to them linux can now call itself "beerware" :-)

Make the page allocator use a free page list instead of a silly
linear search.

Add sys_vhangup() and stubs for send/rcv/sendto/recvfrom/shutdown.
We're making ready for real networking..

Remove nonworking extfs bitmap allocators. We'll have them in ext2.

[Original announcement below]

Patch 1 is essentially a performance-release, but it also contains some
other patches: Ross Biro's tcp-ip stubs are there (but not the tcpip
subdirectory: alpha-testers should know where to find that), as are the
ext-fs superblock cleanups. The first header-file patch by hlu is also
in there.

The resulting patch is pretty big - it's also not as cleaned up as I'd
like it to be.  The swapping/buffer-block handling heuristics are
better, but could still do with some tuning.  Also, the idle task in
this version doesn't do very much: it will be expanded to do some more
page-table calculations.

I will be unable to hack on linux for a couple of weeks (I'll still
answer mails, read the newsgroup and fix bugs, but no heavy-duty
hacking) due to some "circumstances beyond my control".  That probably
means that this patch is the last one for a while (three weeks) unless
some bad bugs show up.

                Linus

Move <xxx.h> to <linux/xxxx.h>

Variable-sized buffer blocks and dynamic buffer cache allocation. The VM
knows how to shrink it automatically!

Add support for "fast" interrupt handlers for serial lines.

Update copyrights to say 1992 too.

Remove broken VESA video card handling.

Separate out partition handling code ("genhd").

Make init unkillable.

Norwegian keyboard map.

Future Domain SCSI controller driver by Rik Faith.

Changes in 0.97:

 - The VESA-support was removed.  I'd be happy to put it back once it
   works on all hardware.  Instead of the VESA-code, I finally put in
   the automatic SVGA setup patches.  See the top-level Makefile.

 - The IRQ code has solidified, and should work on all machines.  Not
   all of the SCSI drivers use it yet, so I expect patches for that..

 - Serial interrupts are handled slightly differently, and performance
   should be up.  I've sent out a few alpha-releases, and testing seems
   to indicate that's actually true this time.  Reactions have ranged
   from "nice" to "wonderful" :-)

 - The buffer-cache and memory management code has been edited quite a
   bit.  ps/free etc programs that reads kernel memory directly no
   longer work, and even a recompilation won't be enough.  They actually
   need editing before they work.

   The buffer-cache now grows and shrinks dynamically depending on how
   much free memory there is.  Shift+PrintScreen will give some memory
   statistics.  (Ctrl+PrSc gives task-info, ALT+PrSc gives current
   register values).

   The mm code changes removed some race-conditions in the VM code, and
   I also tried to make the Out-of-swapspace error less severe (better
   thrashing-detection etc).

 - The super-block code has been cleaned up.  Especially the extended fs
   needs to be edited a bit to take advantage of the new setup, and I
   expect Remy Card will have a patch out eventually.

 - include-files have been moved around some more: there are still some
   names that clash with the standard headers, but not many.

 - Unswappable processes implemented: by default only 'init' is
   unswappable.  This is a bit safer in low-memory conditions, as at
   least init won't die due to low memory.  I also made killing init
   impossible: if init doesn't recognize a signal, it simply won't get
   it.  Some other changes ("while (1) fork();" won't kill the machine
   for non-root users etc)

 - The new SCSI drivers are in.  These make the kernel noticeably
   bigger, but you can leave them out if you don't want them.

 - The floppy- and hd-drivers print out more debugging-info in case of
   errors: this might be irritating if you have hardware that works, but
   often gives soft-errors.  On the other hand, some old debugging-info
   was removed - notably for user-level protection errors etc.

 - Various minor fixes.  I haven't made cdiffs (and I haven't gotten any
   requests for them, so I probably never will), but they would be
   pretty big.

Things that I didn't have time for:

 - I wanted to rewrite the tty drivers to be more "streams-like" (ie not
   an actual streams-implementation, but some of the ideas from
   streams).  I never got around to it: there was simply too much else
   to do.

 - I got a lot of patches, and some went in, others didn't.  If you
   think your patch was important, please re-send it relative to the new
   version.

I'd like comments on the new system: performance / clarity of code etc.
0.97 should correct all known bugs (at least the ones I know about), but
I guess that's just wishful thinking.

Note that the dynamic buffer-code also handles differently-sized
buffers, but that the rest of the system (block device drivers,
filesystem code etc) cannot yet take advantage of this - there is still
some coding needed.

		Linus

More VFS layer work: remove more special cases, and take advantage of
the virtual VFS functions (close and select).  Add fchown/fchgrp and
[f]truncate.

Orest Zborowski shows up, and works on porting X11 to X.  This needs a
lot of infrastructure support: ioperm() for user-mode IO port access,
and SVR style virtual terminal ioctl's to make porting easier.  Perhaps
more importantly, the mmap() system call shows up, even if it right now
is limited only to a direct /dev/mem remapping.

[Original changelog below]

- truncate/ftruncate/fchmod/fchown system calls

        note that there aren't any library functions for these, so they
        aren't very useful yet...

        [f]truncate needed a change in the logic of the internal
        truncate VFS call - anybody that has any nonstandard filesystem
        probably needs to look it up.

- io-bitmap syscalls giving root-processes access to selected io ports
  from user space.  There is a "ioperm()" system call that lets the
  process select which ports it wants to enable/disable (all ports
  disabled as default) as well as a (standard sysv?) ioctl interface
  that X uses.

        again, no library stubs, but it allows things like reading and
        setting the cmos clock without using /dev/port, as well as
        control over the VGA registers...

- mmap for /dev/mem

        more things needed for X...

- the signal-handling fixes needed for gdb

        These aren't yet complete: serial lines still send signals under
        interrupts that can result in problems (ie ptrace doesn't
        correctly get them), but that's pretty unlikely (and will be
        fixed in the final 0.96).  Breakpoints should work etc..

- multiple shared libraries

        Up to 6 simultaneous shared libraries/process: the patches were
        originally by pmacdona, but they were heavily changed by me, and
        I think they work in a more natural manner now.  One user-level
        change is that the libraries are now checked for read and
        execute permissions for safety-reasons.

- cleaned up special files.

        read/write/ioctl no longer has special-case code: it is all
        handled with tables to functions.  This will mean that the SCSI
        patches won't patch in quite cleanly into 0.96: you'll need to
        add the code that sets up the functions.

        Again: device drivers and vfs-filesystem hackers need to look
        into the changes, although they are pretty logical (earlier
        versions just didn't implement all the vfs-routines)

        Note that the vfs-code for select is still not used: select is
        hardcoded for the devices it supports right now.

- ptrace() has a new interface

        as gdb for versions < 0.95c don't work on the new version, and
        gdb won't work very well at all on 0.95c[+], there was no reason
        not to break ptrace.  Thus 0.96 has a new calling convention for
        ptrace, and the old ptrace library function no longer works.
        I'm including the new ptrace library function at the end of this
        post.

- mount() takes 4 arguments, and checks that only the super-user can
  mount/umount things.

        Happily this shouldn't break any old binaries.

- some general cleanups

The subject pretty much says it all: I've sent out the "weekly patch"
and I'd be very interested in comments. As with patch1, there are some
very fundamental changes in the kernel, and they might have some
problems. I'd want as many as possible to test out linux-0.96c.pl2, as
that has always been the best way to test out the changes. Everything
works on my machine, but that doesn't guarantee it will work on other
setups...

The MAJOR change in 0.96c.pl2 is the totally rewritten sleep/wakeup
code. That, together with the IRQ code introduced in pl1 and slightly
edited in pl2, means that two very fundamental things in the linux
kernel have changed in the last two weeks. The code is cleaner, easier
to add devices to, and hopefully faster, but it's still a bit risky to
change this kind of very low-level behaviour.

Select() is now implemented using the vfs jump tables, and thanks to the
better sleep/wakup interface, select() performance should be noticeably
better. At least xload seems to give lower load-averages, and I hope
ka9q will work better with the new kernel. Note that things like the
tty code doesn't yet take full advantage of the new features the
rewritten sleep offers, but I wanted to get a good testing-release out
before actually tweaking all the routines to use the new interface.

The IRQ routines have changed slightly, and all known bugs are fixed.

While I'm most interested to hear comments about the IRQ and
select/sleep/wakup code, there are a few other changes in pl2:

 - Swiss keyboard support.

 - Screen blanking now only reacts to key-presses and kernel messages:
normal tty output doesn't make the screen unblank.

 - DOS-fs version 5 is in. It wouldn't hurt to try it out. It's
somewhat alpha still, but it seems to work. mtools should be a thing of
the past once the dosfs is a bit more tested.

 - core-file magic number, and a minor bug in ptrace is fixed

 - a bus-mouse is supported. I'd like to hear if it still works after I
did the select() patches "blind" (I can't test it on my machine).

 - iopl changing is possible (but requires root priviledges): this
allows access to all IO ports, as well as the interrupt flag. Don't use
it unless /absolutely/ necessary: a bug in your program will most likely
crash the machine if you are running with IO priviledges. It's needed
for some X VGA drivers.

As a result of all the changes, the diff is pretty big. Apply and build
it with something like:

        cd /usr/src
        zcat linux-0.96c.patch2.Z | patch -p0
        cd linux
        make dep
        make clean
        make Image

assuming you have the 0.96c.pl1 kernel in /usr/src/linux. I've had some
reports that my patches won't always go in cleanly: I know for a fact
that patch1 patches cleanly (I rebuilt 0.96c.pl1 by downloading it all
from banjo), so the error is in your end.

Possible problems:

 - The VESA code in setup.S has some problems. I haven't even looked
into it yet, so if it won't work for you, please either (a) use the
unpatched setup.S from 0.96c, or (b) try to find the problem and tell
me. (b) is preferable, of course. I'd like to have VESA support, but
if the bug isn't found, I'll have to use the non-VESA version for 0.97.

 - The IRQ code in 0.96c.pl1 could overrun the stack if linux got
un-ending interrupt requests, resulting in a re-boot. With pl2, this
shouldn't happen: linux should print out something like "Recursive
interrupt on IRQx. Shutting down" and simply disable the problematic
IRQ line. If you see this message, I'd be very interested to hear about
it (which IRQ, what devices you have, etc).

 - And any new or old bugs I haven't found yet.

I have one report that 0.96c.pl1 has problems with the inode table, and
panics on bootup with a "no more inodes in mem" report. Can anybody
confirm this sighting? I haven't found the reason for it, and haven't
seen it myself. I'm hoping it's an installation problem, but if anybody
else sees the same behaviour, I'm SOL.

            Linus

changed the IRQ routines and the serial code to be easier and cleaner
(and hopefully more efficient) and I thought that would be it. I was
wrong.

I got several patches (and one bug-report) again, and while I haven't
had time to check them all, some of them are in. Fixes:

 - Remy Cards correction to the out-of-space problem with the extended
fs is here. Most people using the ext-fs might already have applied
this patch, in which case you might have problems patching.

 - my ftruncate() fix is here. Again, if you already did the trivial
patch by hand, you'll get errors when patching.

 - almesber's implementation of read-only filesystems is here (after
editing by yours truly). The mount() system call now accepts a flags
integer as well as a pointer to some arbitraty data in user space for
some special mount() calls. The general flags allow (a) read-only
mounting, (b) disabling of suid executables (c) disabling of device
special files and (d) total disabling of executables on a per-filesystem
basis. The filesystem specific mount() info isn't currently used by any
fs, but can be used to specify additional information that depends on a
special fs type (a password or similar would be possible..)

 - the rename() system call had a bug in that it allowed moving over a
directory: I think the code to handle this was lost in the vfs editing,
and although the GNU mv utility checked it, a malicious (or just
unsuspecting) program can destroy the fs using this. Thanks for the
bug-report: it was very easy to add once I saw the problem.

 - support for vesa-standard svga cards in setup.S. I'm unable to test
this, but my svga card still works after the patch, so I left it in in
the hope that it doesn't break for anybody else.

 - various minor editing by me, or minor patches sent in by others.

The full cdiff is almost 50kB compressed, so this is a bigger-than-usual
patch. Hope there are no problems. People who are using the new SCSI
drivers might have problems with my changes to the SCSI irq-setup
changes, so be careful (actually using the original sources might be a
good idea, and then upgrading again). I hope to get the new SCSI
drivers into the kernel soon (definitely in time for 0.98).

I'd be interested to hear comments on serial line performance, bugs,
features, etc. As usual, I'm hoping this release won't contain any new
bugs while fixing all the old ones, but I guess that's likely to happen
right after the first winter olympics in Hell.

            Linus

Ext filesystem support! The VFS layer switchover was successful.
Ext support is a more FFS-like filesystem, although still quite heavily
influenced by my original Minix filesystem.  But it allows much bigger
filesystems (minixfs was limited to 64MB) and many more files (minixfs
had a 16-bit inode number).

Named pipes by Paul Hargrove (using the regular pipe code for actual IO).

[original announcement below]

0.96c is actually what I called patch3 earlier this week, but as the new
features were pretty big and the cdiff's are probably going to be bigger
than the normal patches, I decided I might as well make it a totally new
minor release and make a bootimage and complete source available.

0.96c contains:
 - bugfixes (tty, console driver, pty's, sockets)
 - fifo's (names pipes - Paul Hargrove & editing by me)
 - the alpha extended filesystem (Remy Card)
 - st_blocks implemented (ie du, ls give reasonable if not exact values
   for disk-space used)
 - Makefile cleanups and warnings at compile-time removed

Note that while the extended filesystem code is there, and this kernel
successfully mounts and uses the new filesystem (with long filenames and
>64MB partitions), it's still under testing: I haven't made the mkefs
program available, and the extended filesystem features shouldn't be
used for other than testing right now.

Some of the changes are just cleanups: most of the warnings when
compiling the new kernel should be gone (not counting the scsi code
which is still the old non-cleaned-up version), and the make'ing of the
kernel is more logical now.

The bugfixes include the corrected console.c driver, the socket
corrections (without which X sometimes locks up), some pty semantics
corrections (although I'm still not certain it's correct) and some
editing in the general tty driver (including fixing the bug introduced
in 0.96b.pl2 that caused a reboot with uninitialized tty devices).

While the extended filesystem support isn't "official" yet, I can
happily report that my limited testing hasn't found any problems with
long filenames etc.  It still needs a fsck program, but 1.0 looks like a
real possibility soon.

                Linus

up the problems with some mice by implementing most of the serial line
flags like 5-8 bit characters and parity. It mainly corrects only
serial problems, but there are a couple of other patches in it too: the
fsqrt emulation patch is here, so if you already did it, you'll get a
bad patch for that file (which you can ignore). This patch also changes
all instances of signal-setting to use the "send_sig()" subroutine which
should allow gdb to debug all signals.

Apart from the serial lines, I also cleaned up the general tty-handling
routines slightly and removed at least one race-condition in the tty
code. I don't know if it's noticeable, though.

You'll need patch1 (available from all the normal sites) in order to
apply this one. As usual, I'd like to hear if this patch does help
people, or if there are new problems. This patch will also be available
on the normal ftp sites, but as it was pretty minor, I decided I might
as well include it in the post (uuencoded and compressed).

(I also corrected the all-time favourite bug: linux now reports the
right version number once more..)

            Linus

In article <arumble.709312764@extro.ucc.su.OZ.AU> arumble@extro.ucc.su.OZ.AU
(Anthony Rumble) writes:
>
>YES! I have noticed this VERY exact thing also!

Oh, well: it's a bug in the serial drivers that I have already fixed,
but I haven't done the c-diffs yet. I have rewritten big parts of the
serial line code to be more easily configured for different IRQ numbers,
and I noticed the bug while doing that. I'll make patch1 for 0.96b
available later today or tomorrow.

patch1 will be mostly just the serial driver code: it allows changing
the irq's (and port addresses) of serial devices on the fly (with an
ioctl call), so people that have ser4 on irq5 etc shouldn't have to
recompile the kernel. It also returns EBUSY if you try to open a serial
line that shares the irq-line with another line etc.

Another change in patch1 will the the handling of ctrl-alt-del: it will
send a SIGINT to the init process if the reset-function is disabled.
This makes it ideal for a controlled shutdown, but it does need a
/bin/init that knows about this.

            Linus

PS. It seems both the DOS-fs and the extended fs will be out for
alpha-testing next week, so I assume 0.97 will have them both if things
work out ok.

First cut at core-dumping.  Also, do more dynamic boottime memory
allocation, rather than allocating data structures statically.

Allocate task structures at run-time rather than having a big array of
them.

First "obsolete" system call.  The old "stat()" system call was too
limited, due to "struct stat" having various 16-bit fields etc (notably
inode numbers).  We make a new stat() function, and keep the old one
around as "old_stat()" for binary compatibility.

We also need a bigger "utsname" to hold real node names.

Whoo! NR_OPEN is now 32 rather than 20.

itimer() support driven by X11 adoption (Darren Senn).

gcc starts using fsqrt, so that gets added to the FP emulation.  We're
still basing that on my trivial code.

[Original changelog below]

0.96b is not a new major release: it's pretty close to 0.96a with all my
patches (1-4).  However, as there has been 4 patches already, I decided
it would be time for a full kernel release along with a bootimage, so
that people who don't feel confident with patching can use the new
features.

If you already have 0.96a patchlevel 4, 0.96b will offer you these new
features:

 - the math-emulation now handles fsqrt, as gcc-2.2.2 generates that
   inline.  I haven't tested the kernel code at all: I tested the
   algorithm in user space, but I'm lazy, so I never turned off my 387
   to do real testing.  I hope it works.
 - better vt100 terminal emulation thanks to Mika Liljeberg.
 - I removed a possible race-condition in the buffer-cache code.
 - minor fixes

The vt100 emulation should now be complete enough for almost everything
(including vt100 test suites): as a result the setterm utility had to be
changed (as the old setterm codes aren't compatible with the full vt100
codes).  setterm-0.96b.tar.Z contains the new setterm.

The soon-to-be-released gcc-2.2.2 will need the 0.96b kernel: (a) due to
the fsqrt emulation and (b) it uses the new stat() system call.  So
upgrading is a good idea.  (If you have a co-processor, (a) isn't used,
but (b) still stands)

If you have an unpatched 0.96a, the differences to 0.96b are roughly
(not counting the above-mentioned new things):

 - corrected the disk-buffer-list bug with read/write-errors
 - fixed read-ahead warning messages at end of disk
 - better support for text-mode restoration after running MGR and X
 - full core-dumping, attach/detach etc debugging features
 - 16550A support
 - less low 1MB memory used for kernel structures
 - various minor fixes

Note that the fact that new versions (pl4 and above) use more memory in
the 1M+ area means that linux will report less free memory (it's used
for buffer-cache instead).  This could concievably be a problem on 2MB
machines.  The standard kernel comes with only 4 pty's though, and if
you use the standard 80x25 text modes instead of svga modes, the VC
buffers will be smaller.  Please contact me if there are problems even
with this minimal setup.

0.96b does /not/ contain: the new scsi drivers, new filesystems or some
other patches I have gotten (ibm character set mode, loop-devices etc).
If you have sent me any other patch, you might want to remind me about
it.

                Linus

Ok, patch4 implements 32-bit inode numbers (and thus the new
stat/lstat/fstat system calls), as well as correcting the bad
rs-performance on some machines that showed up in patch3. It's
currently only on banjo, but I'll copy it around eventually.

Again, you don't miss much if you don't use this patch: it's mainly for
(a) the serial problems and (b) for hlu etc that want to test out the
32-bit interface. It does some other magical tricks as well (uses less
memory in the low 1M region by moving the screen and tty buffer to high
memory), if anybody is interested.

            Linus

Ok, I already announced it on the kernel mailing-list, but I might as
well go all the way. I put out patch3 to 0.96a yesterday, and it's
available on banjo in pub/Linux/Linus, and I'll upload it to the other
normal ftp-sites tonight.

NOTE! Patch3 is (like patch2) more of a kernel-hacker patch: it's just
in case you want to keep up with my kernel. It has some problems with
some serial lines, and if you experience them, I'd like to know what
type of chip you are running (and what linux reports on bootup). If you
don't think patching the kernel is fun, you might as well forget this
and wait for a real release (next month?).

Patch 3 contains:

- support for attaching and detaching processes under gdb (but you need
  a gdb that knows about this).
- 16550A support
- full core-dumping (again, you need a gdb that supports it)
- sockets have no problems with non-root binding etc
- /dev/zero implemented (mknod /dev/zero c 1 5)

None of the patches are very big (the whole patch is 17kB compressed,
most of it attach/detach code), but they are all pretty useful.

The 16550A support means that with the appropriate chip you now should
be able to use the serial ports at much higher speeds, but as mentioned,
it seems to break on some machines.

The detaching isn't perfect yet (I noticed only after making the diffs
that I had forgotten to do some cleanups), but it's not generally a
problem (the code just forgets to give the process back to it's rightful
father).

The patch is relative to the pl2 kernel, so you have to use the earlier
patches first. This time, I've added the lib/itimer.c code.

16550A support was written by tdavis, the correct format of the
core-dumps was written by eric (who also wrote the attach/detach code I
used as an example when implementing it), /dev/zero was written by
almesber. Nice to see good patches: I just did the socket-thing and
rewrote the attaching to suit me.

            Linus

I have just sent off the second patch to 0.96a: it should be on the
normal ftp-sites (nic, tsx-11 and banjo), although the only site which I
can make it directly readable on is banjo, so on the other sites it will
take the site-managers to make the patch available.

Patch 2 implements:

- itimers (by Darren Senn), which are now also used to implement the
  alarm() system call.

- ultrastor scsi driver patches (by gentzel)

- [f]statfs() system call is implemented (so df can be made fs-
  independent). Also some other minor fs-changes for the upcoming new
  filesystem. Patches by Remy Card.

- preliminary core-file dumping code (linux creates a core-file, but
  it's not in the correct format yet [*]).

- minor changes/bugfixes.

While patching in patch1 is a good idea for anybody, patch 2 isn't
really vital. I've made it available just so kernel hackers can keep up
with the kernel I have right now if they wish. Patch 2 is relative to
patch 1: you have to patch that in first.

[*] The current core-file is very simple, and the kernel code is there
just so that some enterprising character can expand it. A core-file
looks like this right now:

offset data
0x0000 "core-dump: regs=\n"
0x0040 struct pt_regs (see <sys/ptrace.c>)
0x0400 "floating-point regs:\n"
0x0440 struct i387 (see <linux/sched.h>)
0x0800 the first 1kB of user-space

Not very practical, but it /might/ help if the X-server dies of a
segmentation fault or similar (you can use pt_regs.eip to see where it
happened). The kernel code is very easy to change to accomodate for the
real core-file format, I just didn't know what it should be.

                Linus

and X11 text-mode restoration.  Thanks to Rick Sladkey for finding the
dup2() bug.

More VFS cleanups.  Minixfs code reorganized to be more logical, and
split up into a few new files.

SCSI support!!

 - Drew Eckhardt does the SCSI stuff, and does the ST01/ST02 lowlevel
   driver.

 - Ultrastor driver by David Gentzel.

 - Tommy Thorn shows up again.  He did the Danish keyboard tables, now
   he does the AHA 1542 driver.  Ten years later we ended up being
   co-workers at Transmeta ;)

First networking code appears: X11 port needs UNIX domain sockets, and
thus the "socketcall()" system call.  It's not really meant for real
networking, although the code will eventually evolve to support that.
Which explains some of the bad early decisions..  ;)

Werner Almerberger starts taking over floppy driver maintenance.  Thank
Gods!

Johan Myreen translates my assembly-level keyboard driver into C code,
and adds support for diacriticals.

OMAGIC a.out format support

Syslog support for the kernel appears.  If I remember correctly, this
was Peter MacDonald, but no mention of that in the sources.

Bruce Evans shows up here quickly.

Bruce was the author of the Minix/386 patches, and had been one of my
sounding boards for my early development, so it was very gratifying to
see him get interested in Linux.  As it turned out, what he was _really_
interested in was the serial driver, and the Linux serial driver was
already in reasonably good shape.

As a result, Bruce went off to work on 386BSD instead (where the serial
driver was truly crappy), but here he worked on some boot loader cleanups.

Bruce was my hero.

Anyway...  More VFS work here: readdir, bmap and ioctl's are now virtual
operations, and the superblock code is properly virtualized.

Other changes:

 - James Wiegand writes initial parallell port printer driver

 - major/minor fault tracking

 - I rewrote big chunks of ptrace.c

Oops.  I had forgotten to change the kernel version number in 0.95 (so
it showed as 0.12).

 - 80x50 console on standard VGA
 - do "memcpy_fromfs()" and "memcpy_tofs()" rather than byte-at-a-time
   to improve performance (inspired by some earlier patches by Keith White)
 - allow select() on many more file descriptors
 - support up to 4 serial ports (and increase buffering size)
 - Branko Lankester helped make extended partitions work and implemented
   DM partition table support

The big deal in the release notes is actually that the root diskette
maintainership had been moved over to Jim Winstead Jr.

This was the first kernel that got released under the GPL (0.12 had a
time-lapse to make sure the people involved accepted the license change:
nobody ever complained).

Because 0.12 had been so successful, this was supposed to be closer to
1.0.  Yeah, right.  1.0 was eventually released almost exactly two years
later..

The big change here is the first signs of a real VFS layer: while the
only available filesystem is still the Minix-compatible one, the code is
factored out, and the Minix-specific stuff is put in its own directory.
You can clearly see how the thing is moving towards having multiple
different filesystems.

The VFS changes also cause cleanups in various drivers, since we end
up having more clear inode operation structure pointer handling.

Superblock handling is still minix-specific..

NOTE! We also have /bin/init finally.  It still falls through to the old
"run shells forever" case if no init can be found, but it's starting to
look a whole more like real UNIX user-land now..

New developers: Ross Biro shows up, and does ptrace.  He will later end
up doing the first-generation networking code.

Other changes:

 - UK and Danish keyboard maps (and the keyboard driver supported
   "Application mode" keys from vt100+)
 - Make sure interrupts clear the 'D'irection flag
 - Floppy driver gets track buffer, which speeds it up immensely.  This
   was done based on patches by Lawrence Foard (entropy@wintermute.wpi.edu)
 - Lots of buffer cache cleanups.
 - support nonblocking pipe file descriptors
 - recursive symlink support
 - sys_swapon() means that we don't have to select the swap device
   at build (or boot) time ("Written 01/25/92 by Simmule Turner, heavily
   changed by Linus")
 - start some generic timer work (ugh, but these first timers were
   _horrible_ hardcoded things)
 - ptrace for debugging
 - console size query support with TIOC[G|S]WINSZ
 - /dev/kmem ("by Damiano")
 - rebooting (with ctrl-alt-del or sys_reboot()).

From the release notes:

              New features of 0.95, in order of appearance
                      (ie in the order you see them)

      Init/login

Yeah, thanks to poe (Peter Orbaeck (sp?)), linux now boots up like a
real unix with a login-prompt.  Login as root (no passwd), and change
your /etc/passwd to your hearts delight (and add other logins in
/etc/inittab etc).

      Bash is even bigger

It's really a bummer to boot up from floppies: bash takes a long time to
load.  Bash is also now so big that I couldn't fit compress and tar onto
the root-floppy: You'll probably want the old rootimage-0.12 just in
order to get tar+compress onto your harddisk.  If anybody has pointers
to a simple shell that is freely distributable, it might be a good idea
to use that for the root-diskette.

Especially with a small buffer-cache, things aren't fun. Don't worry:
linux runs much better on a harddisk.

      Virtual consoles on any (?) hardware.

You can select one of several consoles by pressing the left alt-key and
a function key at the same time. Linux should report the number of
virtual consoles available upon bootup. /dev/tty0 is now "the current"
screen, /dev/tty1 is the main console, and /dev/tty2-8 can exist
depending on your text-mode or card.

The virtual consoles also have some new screen-handling commands: they
confirm even better to vt200 control codes than 0.11. Special graphic
characters etc: you can well use them as terminals to VMS (although
that's a shameful waste of resources), and the PF1-4 keys work somewhat
in the application-key mode.

      Symbolic links.

0.95 now allows symlinks to point to other symlinks etc (the maximum
depth is a rather arbitrary 5 links). 0.12 didn't like more than one
level of indirection.

      Virtual memory.

VM under 0.95 should be better than under 0.12: no more lockups (as far
as I have seen), and you can now swap to the filesystem as well as to a
special partition. There are two programs to handle this: mkswap to set
up a swap-file/partition and swapon to start up swapping.

mkswap needs either a partition or a file that already exists to make a
swap-area. To make a swap-file, do this:

      # dd bs=1024 count=NN if=/dev/hda of=swapfile
      # mkswap swapfile NN

The first command just makes a file that is NN blocks long (initializing
it from /dev/hda, but that could be anything). The second command then
writes the necessary setup-info into the file. To start swapping, write

      # swapon swapfile

NOTE! 'dd' isn't on the rootdisk: you have to install some things onto
the harddisk before you can get up and running.

NOTE2! When linux runs totally out of virtual memory, things slow down
dramatically. It tries to keep on running as long as it can, but at
least it shouldn't lock up any more. ^C should work, although you might
have to wait a while for it..

      Faster floppies

Ok, you don't notice this much when booting up from a floppy: bash has
grown, so it takes longer to load, and the optimizations work mostly
with sequential accesses.  When you start un-taring floppies to get the
programs onto your harddisk, you'll notice that it's much faster now.
That should be about the only use for floppies under a unix: nobody in
their right mind uses floppies as filesystems.

      Better FS-independence

Hopefully you'll never even notice this, but the filesystem has been
partly rewritten to make it less minix-fs-specific. I haven't
implemented all the VFS-patches I got, so it's still not ready, but it's
getting there, slowly.

      And that's it, I think.

Happy hacking.

                      Linus (torvalds@kruuna.helsinki.fi)

This was created from a re-packaged 0.12 tree

Major milestone! Over the christmas break, I implemented paging to disk,
meaning that you could actually use gcc on a 2MB system.  Some poor sod
(Robert Blum) wanted to use Linux on such a system, and couldn't get the
kernel to compile with anything less "bloated" than gcc.

[ Irony alert: this was back when gcc worked fine on a system with just
  4MB.  Gone are those days. _Loong_ gone. ]

The task size was still limited to 63 tasks of at most 64MB each, but
other than that we were actually getting usable.

Together with other improvements and fixes, 0.12 was actually a very
nice kernel.  It was by now clearly more usable than Minix, which caused
us to think that a 1.0 release was imminent.  The next kernel version
was to be named 0.95, which turned out to be less than a stellar idea.

This was also the point where we changed the copyright license.  See the
attached original release notes.

Other changes:

 - Ted Ts'o continued on his rampage, and implemented BSD process
   control (ie ^Z) etc.  This also introduced the process tree code,
   with pointers between parents and children, rather than iterating
   over the whole list of processes.

 - Ted also did SVR4-style "saved uid/gid" handling.

 - use the C preprocessor for assembly files, cleaning up a lot of
   duplicate definitions etc.

 - better boot loader diagnostics

 - boot sequence now can change the size of the text display.  Who the
   hell is d88-man?

 - fix nasty race condition between "truncate" and file IO.

 - add support for shared libraries with the "uselib()" system call.
   This (together with the fact that we could share clean executable
   pages) cut down on memory usage a lot.

 - supplemental group support.  Hey, what can I say? Unix users expected
   them.

 - symbolic link handling.  This was the first real extension to the
   standard Minix disk layout, and was made possible by the fact that I
   had written my own "mkfs" and "fsck".  Before that, we were still on
   crutches, in that a Linux system depended on a Minix installation for
   these fundamental system tools.

 - mkdir()/rmdir() isn't just for root, you know..  (Yes, seriously.
   Old-style UNIX used to limit them to root-only, since they were just
   special sequences of mknod's)

 - Virtual terminals by Peter MacDonald (who was to do the SLS
   distribution).

   Before having X, this was a _big_ deal.  The fact that Linux had
   virtual terminals with a good vt100 emulation actually made Linux
   stand out even among some of the big commercial unixes.  The Linux
   console was just _so_ much more pleasant to use that it isn't even
   funny.

 - first implementation of "select()", virtual terminals, and pty's.

   These too were originally done by Peter MacDonald, based on some
   patches that had been floating around for Minix for a long time (but
   were never accepted into Minix).

   They didn't get accepted into Linux either, but the patches _did_ end
   up inspiring me to re-do the select/pty parts in a way that was more
   palatable to me.

 - restartable system calls

   This was needed for Ted's code to do ^Z

 - Math emulation! The code was a total crock, and didn't bother with
   such unnecessary niceties as getting rounding right (or, to be
   honest, even getting more than about 60 bits right), but let's face
   it: it was enough to get work done.

   My math emulation was eventually to be entirely replaced by a much
   more complete, and much more precise implementation by Bill
   Metzenthen.  But my original stupid implementation actually ended
   living on at least for a while in BSD - I ended up making it
   available to the BSD people who couldn't use Bill's much better
   implementation due to licensing reasons.  I don't know whatever
   eventually happened to it.

 - support alignment check on i486+. Nobody seems to have ever used it,
   though.

Original release notes:

         RELEASE NOTES FOR LINUX v0.12

This is file mostly contains info on changed features of Linux, and
using old versions as a help-reference might be a good idea.

         COPYRIGHT

The Linux copyright will change: I've had a couple of requests to make
it compatible with the GNU copyleft, removing the "you may not
distribute it for money" condition.  I agree.  I propose that the
copyright be changed so that it confirms to GNU - pending approval of
the persons who have helped write code.  I assume this is going to be no
problem for anybody: If you have grievances ("I wrote that code assuming
the copyright would stay the same") mail me.  Otherwise The GNU copyleft
takes effect as of the first of February.  If you do not know the gist
of the GNU copyright - read it.

         INSTALLATION

This is a SHORT install-note. The installation is very similar to 0.11,
so read that (INSTALL-0.11) too. There are a couple of programs you will
need to install linux: something that writes disk images (rawrite.exe or
NU or...) and something that can create harddisk partitions (fdisk under
xenix or older versions of dos, edpart.exe or something like that).

NOTE! Repartitioning your harddisk will destroy all data on it (well,
not exactly, but if you know enough to get back the data you probably
didn't need this warning).  So be careful.

READ THIS THROUGH, THEN READ INSTALL-0.11, AND IF YOU ARE SURE YOU KNOW
WHAT YOU ARE DOING, CONTINUE.  OTHERWISE, PANIC.  OR WRITE ME FOR
EXPLANATIONS.  OR DO ANYTHING BUT INSTALL LINUX - IT'S VERY SIMPLE, BUT
IF YOU DON'T KNOW WHAT YOU ARE DOING YOU'LL PROBABLY BE SORRY.  I'D
RATHER ANSWER A FEW UNNECESSARY MAILS THAN GET MAIL SAYING "YOU KILLED
MY HARDDISK, BASTARD.  I'M GOING TO FIND YOU, AND YOU'LL BE SORRY WHEN I
DO".

1) back up everything you have on your harddisk - linux-0.12 is still in
   beta and might do weird things.  The only thing I guarantee is that
   it has worked fine on /my/ machine - for all I know it might eat your
   harddisk and spit it out in small pieces on any other hardware.

2) Test out the linux boot-disk with the root file system.  If it
   doesn't work, check the hardware requirements, and mail me if you
   still think it should work.  I might not be able to help you, but
   your bug-report would still be appreciated.

   Test that linux can read your harddisk at least partly: run the fdisk
   program on the root-disk, and see if it barfs.  If it tells you about
   any partitions at all, linux can successfully read at least part of
   your harddisk.

3) Make sure that you have a free /primary/ partition.  There can be 4
   primary partitions per drive: newer DOS fdisks seem to be able to
   create only 2 (one primary and one extended).  In that case use some
   other partitioning software: edpart.exe etc.  Linux fdisk currently
   only tells you the partition info - it doesn't write to the disk.

   Remember to check how big your partition was, as that can be used to
   tell which device Linux thinks it is.

4) Boot up linux again, fdisk to make sure you now have the new
   partition, and use mkfs to make a filesystem on one of the partitions
   fdisk reports.  Write "mkfs -c /dev/hdX nnn" where X is the device
   number reported by linux fdisk, and nnn is the size - also reported
   by fdisk.  nnn is the size in /blocks/, ie kilobytes.  You should be
   able to use the size info to determine which partition is represented
   by which device name.

5) Mount the new disk partition: "mount /dev/hdX /user".  Copy over the
   root filesystem to the harddisk, eg like this:

        # for i in bin dev etc usr tmp
        # do
        # cp +recursive /$i /user
        # done

   You caanot use just "cp +recursive / /user", as that will result in a
   loop.

6) Sync the filesystem after you have played around enough, and reboot.

        # sync
        <wait for it to sync>
        ctrl-alt-del

   The folklore says you should do this three times before rebooting:
   once should be enough, but I admit I do it three times anyway :) THIS
   IS IMPORTANT! NEVER EVER FORGET TO SYNC BEFORE KILLING THE MACHINE.

7) Change the bootdisk to understand which partition it should use as a
   root filesystem.  See INSTALL-0.11: it's still the word at offset
   508 into the image. You should be up and running.

That's it. Go back and read the INSTALL-0.11

         New features of 0.12, in order of appearance
         (ie in the order you see them)

        Linux now prints cute dots when loading

WoW. Run, don't walk, to see this :). Seriously, it should hopefully now
load even on machines that never got off the ground before, but
otherwise the loading hasn't changed. Implemented by drew.

        Super-VGA detection for extended alphamun modes

I cannot guarantee it, I didn't write it, but it works great on a ET400
SVGA card.  I'm addicted to the new look with 100x40 character editing,
instead of a cramped 80x25.  This only works on VGA-cards that support
higher text-resolutions, and which are correctly identified. Implemented
by d88-man.

        Job Control.

Ok, everybody used to typing ^Z after they started a long command, and
forgot to put it in the background - now it works on linux too.  Bash
knows the usualy job-control commands: bg, fg, jobs & kill.  I hope
there will be no nasty surprises.  Job control was implemented by
tytso@athena.mit.edu.

        Virtual consoles on EGA/VGA screens.

You can select one of several consoles by pressing the left alt-key and
a function key at the same time. Linux should report the number of
virtual consoles available upon bootup. /dev/tty0 is now "the current"
screen, /dev/tty1 is the main console, and /dev/tty2-8 can exist
depending on your text-mode or card.

NOTE! Scrolling is noticeably much slower with virtual consoles on a
EGA/VGA. The reason is that no longer does linux use all the screen
memory as a long buffer, but crams in several consoles in it. I think
it's worth it.

The virtual consoles also have some new screen-handling commands: they
confirm even better to vt200 control codes than 0.11. Special graphic
characters etc: you can well use them as terminals to VMS (although
that's a shameful waste of resources).

        pty's

Ok. I have to admit that I didn't get the hangup-code working correctly,
but that should be easy to add. The general things are there.

        select

I've never used it, so I cannot say how well it works. My minor testing
seems to indicate that it works ok. vc's, pty's and select were
implemented by pmacdona, although I hacked it heavily.

        387-emulation.

It's not complete, but it works well enough to run those gcc2.0 compiled
programs I tested (few).  None of the "heavy" math-functions are
implemented yet.

        Symbolic links.

Try out a few "ln -s xx yy", and ls -l. Note that I think tar should be
recompiled to know anout them, and probably some other programs too. The
0.12 rootimage-disk has most of the recompiled fileutilities.

        Virtual memory.

In addition to the "mkfs" program, there is now a "mkswap" program on
the root disk.  The syntax is identical: "mkswap -c /dev/hdX nnn", and
again: this writes over the partition, so be careful.  Swapping can then
be enabled by changing the word at offset 506 in the bootimage to the
desired device.  Use the same program as for setting the root file
system (but change the 508 offset to 506 of course).

NOTE! This has been tested by Robert Blum, who has a 2M machine, and it
allows you to run gcc without much memory.  HOWEVER, I had to stop using
it, as my diskspace was eaten up by the beta-gcc-2.0, so I'd like to
hear that it still works: I've been totally unable to make a
swap-partition for even rudimentary testing since about christmastime.
Thus the new changes could possibly just have backfired on the VM, but I
doubt it.

        And that's it, I think.

Happy hacking.

         Linus

This was created from a re-packaged 0.11 tree.

Linux-0.11 has a few rather major improvements, but perhaps most
notably, is the first kernel where some other people start making
real contributions.

 - I fixed the buffer cache code, making it a lot more stable

 - demand-loading from disk. My comment proudly states:

        Once more I can proudly say that linux stood up to being changed: it
        was less than 2 hours work to get demand-loading completely implemented.

   This is a major milestone, since it makes the kernel much more
   powerful than Minix was at the time.  I also share clean pages.

 - we still don't have an /sbin/init, but we now load /etc/rc at bootup,
   and the kernel will loop, spawning shells forever. That makes it easier
   to test things.

 - scaffolding for math emulation introduced.

 - Ted Ts'o shows up as a coder. Ted implements:
        o "#!" escape handling for executables
        o fixes for some file permission handling
        o "sticky" directory bit
        o first "malloc()/free()" implementation.
          (this one is horrible: the free needs the size for good
           performance, which will result in years of "free_s()" pains)
        o adds BSD-style setreuid/gid() handling
        o allows us to specify root device at image build time
        o cleanups of some of the uglier direct %fs-register accesses

 - Galen Hunt shows up as a coder: he's added code to handle different
   video card detection (whereas my original one just handled VGA, we
   now handle CGA, MGA, EGA and VGA)

 - The console can beep now: John T Kohl (who also does the tty KILL
   char handling)

 - we also now have German (Wolfgang Thiel) and French (Marc Corsini)
   keyboard maps.  World Domination!

Btw, if you wonder what the "Urgel" comments are - I was still fairly
Swedish-speaking, and "Urgel" is what I would these days write as "Ugh".

It's a sign of trouble or ugly code.  The floppy driver in particular is
clearly not something I'm very proud of ;).

Likely correct 0.10: these were re-created from the RCS tree that Ted
Ts'o had, no known pristine 0.10 tree (or, sadly, 0.02 and 0.03 trees)
exist any more.

Linux-0.10 was actually a major step.  It was _almost_ able to host
itself, and if I remember correctly, a small patch I posted to the
newsgroup a few days later got the buffer cache handling stable enough
that Linux could now compile itself under itself without running out of
memory due to a memory leak.

Apart from bugfixes, the major update here is the support for
mount/umount.  But you can also tell that others are starting to test
out this thing, since the harddisk geometry is now auto-sensed, and we
support the US keyboard layout in addition to the Finnish one.

(This is also the first actual thing from the outside: the US keyboard
layout tables came from Alfred Leung, although with major editing by me.)

 - add copyright messages ("(C) 1991  Linus Torvalds")

   Nobody else is really doing coding (yet..) but clearly I'm starting
   to be a lot more aware of other people here.

 - split up boot/boot.s into boot/bootsect.s and boot/setup.s
 - autodetect floppy type for booting
 - make root device and boot device configurable

 - support up to 16MB of physical memory (instead of just 8MB ;)

   Whee. We're clearly moving into the "big iron" phase of Linux.

 - move drivers around.  We now have separate subdirectories for
   character device drivers (tty and memory) and block device drivers.

 - initial floppy driver support!

   You can see how the "block layer" interfaces evolved directly from
   moving parts of the original hd.c driver into ll_rw_block.c and
   making them "generic".

 - make file reading do simple read-ahead
 - make file writing avoid reading in blocks that are totally overwritten
 - add support for /dev/port and /dev/null (!!)
 - improve pipe throughput

 - add support for sigaction(), not just old-style signal()

   This also rewrites most of the signal code in C rather than assembly.

 - add "mknod()" and "mount()"/"umount()" system calls, and support
   for traversing over mount-points.

 - add "sessions" and setsid(), so that we get proper SIGHUP's

This is the initial 0.01 kernel as found on various history sites.

Fun facts:

 - kernel/Makefile still calls it the FREAX kernel

 - this was in a more innocent age, when the only copyright notice
   is a single "(C) 1991 Linus Torvalds" in lib/string.h

 - the keyboard driver was still in all assembly language, with a
   hardcoded map for (7-bit) Finnish keyboards. At least I had converted
   the VT100 emulation from assembly to C. Too bad I didn't keep the
   _really_ old code around for historical interest.

 - All the early kernels wanted a special version of gcc to compile: I
   had made extensions to gcc-1.40 to make it use the x86 string
   instructions for things like "memcpy()" using the "-mstring-insns"
   command line option.

 - Also, note that newer versions of gcc (which do have the inline
   intrisics, quite independently of my early -mstring-insns hack) will
   not accept the code: it needs a compiler that outputs old-style a.out
   format, and that accepts some of the strange inline assembly that I
   used.

 - In short: you really need some stone-age tools to actually compile
   this, if you actually want to.  And if you actually want to _run_ it
   too, you need to have some old hardware and most likely edit some of
   the hardcoded numbers too.  The harddisk driver has two different
   hardcoded settings: my harddisk, and Lasu's harddisk.

Statistics:

It's 88 files with about ten thousand lines, written by yours truly
except for the vsprintf routine which was co-written with Lars
Wirzenius.  Lasu wasn't as huge a fan of inline assembly as I was, thus
the comment

        "Wirzenius wrote this portably, Torvalds fucked it up :-)"

I think that comment pretty much sums it up ;)

Original release notes for 0.01 follow:

         Notes for linux release 0.01

         0. Contents of this directory

linux-0.01.tar.Z - sources to the kernel
bash.Z - compressed bash binary if you want to test it
update.Z - compressed update binary
RELNOTES-0.01 - this file

         1. Short intro

This is a free minix-like kernel for i386(+) based AT-machines.  Full
source is included, and this source has been used to produce a running
kernel on two different machines.  Currently there are no kernel
binaries for public viewing, as they have to be recompiled for different
machines.  You need to compile it with gcc (I use 1.40, don't know if
1.37.1 will handle all __asm__-directives), after having changed the
relevant configuration file(s).

As the version number (0.01) suggests this is not a mature product.
Currently only a subset of AT-hardware is supported (hard-disk, screen,
keyboard and serial lines), and some of the system calls are not yet
fully implemented (notably mount/umount aren't even implemented).  See
comments or readme's in the code.

This version is also meant mostly for reading - ie if you are interested
in how the system looks like currently.  It will compile and produce a
working kernel, and though I will help in any way I can to get it
working on your machine (mail me), it isn't really supported.  Changes
are frequent, and the first "production" version will probably differ
wildly from this pre-alpha-release.

Hardware needed for running linux:
        - 386 AT
        - VGA/EGA screen
        - AT-type harddisk controller (IDE is fine)
        - Finnish keyboard (oh, you can use a US keyboard, but not
          without some practise :-)

The Finnish keyboard is hard-wired, and as I don't have a US one I
cannot change it without major problems. See kernel/keyboard.s for
details. If anybody is willing to make an even partial port, I'd be
grateful. Shouldn't be too hard, as it's tabledriven (it's assembler
though, so ...)

Although linux is a complete kernel, and uses no code from minix or
other sources, almost none of the support routines have yet been coded.
Thus you currently need minix to bootstrap the system. It might be
possible to use the free minix demo-disk to make a filesystem and run
linux without having minix, but I don't know...

         2. Copyrights etc

This kernel is (C) 1991 Linus Torvalds, but all or part of it may be
redistributed provided you do the following:

        - Full source must be available (and free), if not with the
          distribution then at least on asking for it.

        - Copyright notices must be intact. (In fact, if you distribute
          only parts of it you may have to add copyrights, as there aren't
          (C)'s in all files.) Small partial excerpts may be copied
          without bothering with copyrights.

        - You may not distibute this for a fee, not even "handling"
          costs.

Mail me at "torvalds@kruuna.helsinki.fi" if you have any questions.

Sadly, a kernel by itself gets you nowhere. To get a working system you
need a shell, compilers, a library etc. These are separate parts and may
be under a stricter (or even looser) copyright. Most of the tools used
with linux are GNU software and are under the GNU copyleft. These tools
aren't in the distribution - ask me (or GNU) for more info.

         3. Short technical overview of the kernel.

The linux kernel has been made under minix, and it was my original idea
to make it binary compatible with minix. That was dropped, as the
differences got bigger, but the system still resembles minix a great
deal. Some of the key points are:

        - Efficient use of the possibilities offered by the 386 chip.
          Minix was written on a 8088, and later ported to other
          machines - linux takes full advantage of the 386 (which is
          nice if you /have/ a 386, but makes porting very difficult)

        - No message passing, this is a more traditional approach to
          unix. System calls are just that - calls. This might or might
          not be faster, but it does mean we can dispense with some of
          the problems with messages (message queues etc). Of course, we
          also miss the nice features :-p.

        - Multithreaded FS - a direct consequence of not using messages.
          This makes the filesystem a bit (a lot) more complicated, but
          much nicer. Coupled with a better scheduler, this means that
          you can actually run several processes concurrently without
          the performance hit induced by minix.

        - Minimal task switching. This too is a consequence of not using
          messages. We task switch only when we really want to switch
          tasks - unlike minix which task-switches whatever you do. This
          means we can more easily implement 387 support (indeed this is
          already mostly implemented)

        - Interrupts aren't hidden. Some people (among them Tanenbaum)
          think interrupts are ugly and should be hidden. Not so IMHO.
          Due to practical reasons interrupts must be mainly handled by
          machine code, which is a pity, but they are a part of the code
          like everything else. Especially device drivers are mostly
          interrupt routines - see kernel/hd.c etc.

        - There is no distinction between kernel/fs/mm, and they are all
          linked into the same heap of code. This has it's good sides as
          well as bad. The code isn't as modular as the minix code, but
          on the other hand some things are simpler. The different parts
          of the kernel are under different sub-directories in the
          source tree, but when running everything happens in the same
          data/code space.

The guiding line when implementing linux was: get it working fast. I
wanted the kernel simple, yet powerful enough to run most unix software.
The file system I couldn't do much about - it needed to be minix
compatible for practical reasons, and the minix filesystem was simple
enough as it was. The kernel and mm could be simplified, though:

        - Just one data structure for tasks. "Real" unices have task
          information in several places, I wanted everything in one
          place.

        - A very simple memory management algorithm, using both the
          paging and segmentation capabilities of the i386. Currently
          MM is just two files - memory.c and page.s, just a couple of
          hundreds of lines of code.

These decisions seem to have worked out well - bugs were easy to spot,
and things work.

         4. The "kernel proper"

All the routines handling tasks are in the subdirectory "kernel". These
include things like 'fork' and 'exit' as well as scheduling and minor
system calls like 'getpid' etc. Here are also the handlers for most
exceptions and traps (not page faults, they are in mm), and all
low-level device drivers (get_hd_block, tty_write etc). Currently all
faults lead to a exit with error code 11 (Segmentation fault), and the
system seems to be relatively stable ("crashme" hasn't - yet).

         5. Memory management

This is the simplest of all parts, and should need only little changes.
It contains entry-points for some things that the rest of the kernel
needs, but mostly copes on it's own, handling page faults as they
happen. Indeed, the rest of the kernel usually doesn't actively allocate
pages, and just writes into user space, letting mm handle any possible
'page-not-present' errors.

Memory is dealt with in two completely different ways - by paging and
segmentation.  First the 386 VM-space (4GB) is divided into a number of
segments (currently 64 segments of 64Mb each), the first of which is the
kernel memory segment, with the complete physical memory identity-mapped
into it.  All kernel functions live within this area.

Tasks are then given one segment each, to use as they wish. The paging
mechanism sees to filling the segment with the appropriate pages,
keeping track of any duplicate copies (created at a 'fork'), and making
copies on any write. The rest of the system doesn't need to know about
all this.

         6. The file system

As already mentioned, the linux FS is the same as in minix. This makes
crosscompiling from minix easy, and means you can mount a linux
partition from minix (or the other way around as soon as I implement
mount :-). This is only on the logical level though - the actual
routines are very different.

        NOTE! Minix-1.6.16 seems to have a new FS, with minor
        modifications to the 1.5.10 I've been using. Linux
        won't understand the new system.

The main difference is in the fact that minix has a single-threaded
file-system and linux hasn't. Implementing a single-threaded FS is much
easier as you don't need to worry about other processes allocating
buffer blocks etc while you do something else. It also means that you
lose some of the multiprocessing so important to unix.

There are a number of problems (deadlocks/raceconditions) that the linux
kernel needed to address due to multi-threading.  One way to inhibit
race-conditions is to lock everything you need, but as this can lead to
unnecessary blocking I decided never to lock any data structures (unless
actually reading or writing to a physical device).  This has the nice
property that dead-locks cannot happen.

Sadly it has the not so nice property that race-conditions can happen
almost everywhere.  These are handled by double-checking allocations etc
(see fs/buffer.c and fs/inode.c).  Not letting the kernel schedule a
task while it is in supervisor mode (standard unix practise), means that
all kernel/fs/mm actions are atomic (not counting interrupts, and we are
careful when writing those) if you don't call 'sleep', so that is one of
the things we can count on.

         7. Apologies :-)

This isn't yet the "mother of all operating systems", and anyone who
hoped for that will have to wait for the first real release (1.0), and
even then you might not want to change from minix.  This is a source
release for those that are interested in seeing what linux looks like,
and it's not really supported yet.  Anyone with questions or suggestions
(even bug-reports if you decide to get it working on your system) is
encouraged to mail me.

         8. Getting it working

Most hardware dependancies will have to be compiled into the system, and
there a number of defines in the file "include/linux/config.h" that you
have to change to get a personalized kernel.  Also you must uncomment
the right "equ" in the file boot/boot.s, telling the bootup-routine what
kind of device your A-floppy is.  After that a simple "make" should make
the file "Image", which you can copy to a floppy (cp Image /dev/PS0 is
what I use with a 1.44Mb floppy).  That's it.

Without any programs to run, though, the kernel cannot do anything. You
should find binaries for 'update' and 'bash' at the same place you found
this, which will have to be put into the '/bin' directory on the
specified root-device (specified in config.h). Bash must be found under
the name '/bin/sh', as that's what the kernel currently executes. Happy
hacking.

         Linus Torvalds "torvalds@kruuna.helsinki.fi"
         Petersgatan 2 A 2
         00140 Helsingfors 14
         FINLAND