Commit:     4ee5b10abeb2b5581be10d3022694cd19084e9b0
Parent:     ff0ce6845bc18292e80ea40d11c3d3a539a3fc5e
Author:     H. Peter Anvin <[EMAIL PROTECTED]>
AuthorDate: Thu Sep 27 17:17:12 2007 -0700
Committer:  H. Peter Anvin <[EMAIL PROTECTED]>
CommitDate: Fri Sep 28 10:12:44 2007 -0700

    [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
    Signed-off-by: H. Peter Anvin <[EMAIL PROTECTED]>
 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 bccaa1c..3783539 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
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