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| author | H. Peter Anvin <hpa@zytor.com> | 2009-05-21 16:03:15 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2009-05-21 16:03:15 -0700 |
| commit | afef2c845b93ebe52c178a5a42d498be75fb4c8c (patch) | |
| tree | 8e914b01ea0cc2931a4cb0c8455223405fea642b /core | |
| parent | 044154a0479cd365597846dd7025755eb852d76f (diff) | |
| download | syslinux.git-afef2c845b93ebe52c178a5a42d498be75fb4c8c.tar.gz syslinux.git-afef2c845b93ebe52c178a5a42d498be75fb4c8c.tar.xz syslinux.git-afef2c845b93ebe52c178a5a42d498be75fb4c8c.zip | |
Drop support for ACPI 3 E820 extended memory attributes
Drop all support for ACPI 3 E820 extended memory attributes. There
are BIOSes in the field that report completely bogus information here,
resulting in no memory at all being detected (we then fall back to
E801 detection, but that is problematic in its own ways.)
There is strong reasons to believe at this point that the extended
memory attributes are not usable in their current form, so drop them
and revert back to simple 20-byte support, including for MEMDISK
spoofing.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'core')
| -rw-r--r-- | core/highmem.inc | 19 |
1 files changed, 6 insertions, 13 deletions
diff --git a/core/highmem.inc b/core/highmem.inc index c7e602f8..1f8349bd 100644 --- a/core/highmem.inc +++ b/core/highmem.inc @@ -43,9 +43,8 @@ get_e820: .start_over: mov di,E820Buf xor ax,ax - mov cx,12 + mov cx,10 rep stosw ; Clear buffer - mov byte [di-4],01h ; Initial extattr value xor ebx,ebx ; Start with first record jmp short .do_e820 ; Skip "at end" check first time! .int_loop: and ebx,ebx ; If we're back at beginning... @@ -53,7 +52,7 @@ get_e820: .do_e820: mov eax,0000E820h mov edx,534D4150h ; "SMAP" backwards xor ecx,ecx - mov cl,24 ; ECX <- 24 (size of buffer) + mov cl,20 ; ECX <- 20 (size of buffer) mov di,E820Buf int 15h jnc .no_carry @@ -64,15 +63,9 @@ get_e820: .no_carry: cmp eax,534D4150h jne no_e820 - cmp cl,24 - jb .no_ext_attr - ; - ; Some blithering idiot added a whole new field to E820, - ; completely without regard for its implications... - ; - test byte [E820Buf+20],1 ; AddressRangeEnabled - jz .not_ram -.no_ext_attr: + cmp cx,20 + jb no_e820 + ; ; Look for a memory block starting at <= 1 MB and continuing upward ; @@ -159,7 +152,7 @@ got_highmem: section .bss alignb 4 -E820Buf resd 6 ; INT 15:E820 data buffer +E820Buf resd 5 ; INT 15:E820 data buffer E820Mem resd 1 ; Memory detected by E820 E820Max resd 1 ; Is E820 memory capped? HighMemSize resd 1 ; End of memory pointer (bytes) |