Commit 320a6b2e authored by Alexander van Heukelum's avatar Alexander van Heukelum Committed by Ingo Molnar

x86: reserve end-of-conventional-memory to 1MB, 64-bit

This patch is an add-on to the 64-bit ebda patch. It makes
the functions reserve_ebda_region (renamed from reserve_ebda)
and copy_e820_map equal to the 32-bit versions of the previous
patch.

Changes:

Use u64 and u32 for local variables in copy_e820_map.

The amount of conventional memory and the start of the EBDA are
detected by reading the BIOS data area directly. Paravirtual
environments do not provide this area, so we bail out early
in that case. They will just have to set up a correct memory
map to start with.

Add a safety net for zeroed out BIOS data area.
Signed-off-by: default avatarAlexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent f6eb62b6
...@@ -621,10 +621,10 @@ static int __init copy_e820_map(struct e820entry *biosmap, int nr_map) ...@@ -621,10 +621,10 @@ static int __init copy_e820_map(struct e820entry *biosmap, int nr_map)
return -1; return -1;
do { do {
unsigned long start = biosmap->addr; u64 start = biosmap->addr;
unsigned long size = biosmap->size; u64 size = biosmap->size;
unsigned long end = start + size; u64 end = start + size;
unsigned long type = biosmap->type; u32 type = biosmap->type;
/* Overflow in 64 bits? Ignore the memory map. */ /* Overflow in 64 bits? Ignore the memory map. */
if (start > end) if (start > end)
......
...@@ -55,12 +55,30 @@ static void __init copy_bootdata(char *real_mode_data) ...@@ -55,12 +55,30 @@ static void __init copy_bootdata(char *real_mode_data)
/* /*
* The BIOS places the EBDA/XBDA at the top of conventional * The BIOS places the EBDA/XBDA at the top of conventional
* memory, and usually decreases the reported amount of * memory, and usually decreases the reported amount of
* conventional memory (int 0x12) too. * conventional memory (int 0x12) too. This also contains a
* workaround for Dell systems that neglect to reserve EBDA.
* The same workaround also avoids a problem with the AMD768MPX
* chipset: reserve a page before VGA to prevent PCI prefetch
* into it (errata #56). Usually the page is reserved anyways,
* unless you have no PS/2 mouse plugged in.
*/ */
static __init void reserve_ebda(void) static void __init reserve_ebda_region(void)
{ {
unsigned int lowmem, ebda_addr; unsigned int lowmem, ebda_addr;
/* To determine the position of the EBDA and the */
/* end of conventional memory, we need to look at */
/* the BIOS data area. In a paravirtual environment */
/* that area is absent. We'll just have to assume */
/* that the paravirt case can handle memory setup */
/* correctly, without our help. */
#ifdef CONFIG_PARAVIRT
if ((boot_params.hdr.version >= 0x207) &&
(boot_params.hdr.hardware_subarch != 0)) {
return;
}
#endif
/* end of low (conventional) memory */ /* end of low (conventional) memory */
lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES); lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES);
lowmem <<= 10; lowmem <<= 10;
...@@ -80,8 +98,8 @@ static __init void reserve_ebda(void) ...@@ -80,8 +98,8 @@ static __init void reserve_ebda(void)
lowmem = 0x9f000; lowmem = 0x9f000;
/* Paranoia: should never happen, but... */ /* Paranoia: should never happen, but... */
if (lowmem >= 0x100000) if ((lowmem == 0) || (lowmem >= 0x100000))
lowmem = 0xa0000; lowmem = 0x9f000;
/* reserve all memory between lowmem and the 1MB mark */ /* reserve all memory between lowmem and the 1MB mark */
reserve_early(lowmem, 0x100000, "BIOS reserved"); reserve_early(lowmem, 0x100000, "BIOS reserved");
...@@ -140,7 +158,7 @@ void __init x86_64_start_kernel(char * real_mode_data) ...@@ -140,7 +158,7 @@ void __init x86_64_start_kernel(char * real_mode_data)
reserve_early(ramdisk_image, ramdisk_end, "RAMDISK"); reserve_early(ramdisk_image, ramdisk_end, "RAMDISK");
} }
reserve_ebda(); reserve_ebda_region();
/* /*
* At this point everything still needed from the boot loader * At this point everything still needed from the boot loader
......
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