diff options
| author | H. Peter Anvin <hpa@zytor.com> | 2007-09-27 17:17:12 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2007-09-28 10:12:44 -0700 |
| commit | 4ee5b10abeb2b5581be10d3022694cd19084e9b0 (patch) | |
| tree | e269f4bd3570ee41b94b68974891e51ef011a9f6 | |
| parent | ff0ce6845bc18292e80ea40d11c3d3a539a3fc5e (diff) | |
[x86 setup] Correct the SMAP check for INT 0x15, AX=0xe820
The e820 probe code was checking %edx, not %eax, for the SMAP
signature on return. This worked on *almost* all systems, since %edx
still contained SMAP from the call on entry, but on a handful of
systems it failed -- plus, we would have missed real mismatches.
The error output is "=d" to make sure gcc knows %edx is clobbered
here.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| -rw-r--r-- | arch/i386/boot/memory.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/arch/i386/boot/memory.c b/arch/i386/boot/memory.c index bccaa1cf664..378353956b5 100644 --- a/arch/i386/boot/memory.c +++ b/arch/i386/boot/memory.c @@ -28,11 +28,14 @@ static int detect_memory_e820(void) do { size = sizeof(struct e820entry); - id = SMAP; + + /* Important: %edx is clobbered by some BIOSes, + so it must be either used for the error output + or explicitly marked clobbered. */ asm("int $0x15; setc %0" - : "=am" (err), "+b" (next), "+d" (id), "+c" (size), + : "=d" (err), "+b" (next), "=a" (id), "+c" (size), "=m" (*desc) - : "D" (desc), "a" (0xe820)); + : "D" (desc), "d" (SMAP), "a" (0xe820)); /* Some BIOSes stop returning SMAP in the middle of the search loop. We don't know exactly how the BIOS |