1. 05 Apr, 2009 38 commits
  2. 04 Apr, 2009 2 commits
    • Linus Torvalds's avatar
      Make non-compat preadv/pwritev use native register size · 601cc11d
      Linus Torvalds authored
      Instead of always splitting the file offset into 32-bit 'high' and 'low'
      parts, just split them into the largest natural word-size - which in C
      terms is 'unsigned long'.
      
      This allows 64-bit architectures to avoid the unnecessary 32-bit
      shifting and masking for native format (while the compat interfaces will
      obviously always have to do it).
      
      This also changes the order of 'high' and 'low' to be "low first".  Why?
      Because when we have it like this, the 64-bit system calls now don't use
      the "pos_high" argument at all, and it makes more sense for the native
      system call to simply match the user-mode prototype.
      
      This results in a much more natural calling convention, and allows the
      compiler to generate much more straightforward code.  On x86-64, we now
      generate
      
              testq   %rcx, %rcx      # pos_l
              js      .L122   #,
              movq    %rcx, -48(%rbp) # pos_l, pos
      
      from the C source
      
              loff_t pos = pos_from_hilo(pos_h, pos_l);
      	...
              if (pos < 0)
                      return -EINVAL;
      
      and the 'pos_h' register isn't even touched.  It used to generate code
      like
      
              mov     %r8d, %r8d      # pos_low, pos_low
              salq    $32, %rcx       #, tmp71
              movq    %r8, %rax       # pos_low, pos.386
              orq     %rcx, %rax      # tmp71, pos.386
              js      .L122   #,
              movq    %rax, -48(%rbp) # pos.386, pos
      
      which isn't _that_ horrible, but it does show how the natural word size
      is just a more sensible interface (same arguments will hold in the user
      level glibc wrapper function, of course, so the kernel side is just half
      of the equation!)
      
      Note: in all cases the user code wrapper can again be the same. You can
      just do
      
      	#define HALF_BITS (sizeof(unsigned long)*4)
      	__syscall(PWRITEV, fd, iov, count, offset, (offset >> HALF_BITS) >> HALF_BITS);
      
      or something like that.  That way the user mode wrapper will also be
      nicely passing in a zero (it won't actually have to do the shifts, the
      compiler will understand what is going on) for the last argument.
      
      And that is a good idea, even if nobody will necessarily ever care: if
      we ever do move to a 128-bit lloff_t, this particular system call might
      be left alone.  Of course, that will be the least of our worries if we
      really ever need to care, so this may not be worth really caring about.
      
      [ Fixed for lost 'loff_t' cast noticed by Andrew Morton ]
      Acked-by: default avatarGerd Hoffmann <kraxel@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: linux-api@vger.kernel.org
      Cc: linux-arch@vger.kernel.org
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Ralf Baechle <ralf@linux-mips.org>>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      601cc11d
    • Arjan van de Ven's avatar
      ACPI: battery: asynchronous init · 0f66af53
      Arjan van de Ven authored
      The battery driver tends to take quite some time to initialize
      (100ms-300ms is quite typical).
      This patch initializes the batter driver asynchronously, so that other
      things in the kernel can initialize in parallel to this 300 msec.
      
      As part of this, the battery driver had to move to the back
      of the ACPI init order (hence the Makefile change).
      Without this move, the next ACPI driver would just block
      on the ACPI/devicee layer semaphores until the battery driver was
      done anyway, not gaining any boot time.
      Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
      Signed-off-by: default avatarLen Brown <len.brown@intel.com>
      0f66af53