Messages in this thread Patch in this message | | | Date | Fri, 27 Mar 2009 13:14:41 -0400 | From | "Michael K. Johnson" <> | Subject | [PATCH] mark %esi as clobbered in E820 BIOS call |
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Justin and Peter, please review this for stable .y trees. Peter, please review this for trunk unless you decide to do a more extensive workaround for BIOS register clobbering.
Thanks!
$ cat e820-esi-clobber-workaround.patch Jordan Hargrave diagnosed a BIOS clobbering %esi in the E820 call. That particular BIOS has been fixed, but there is a possibility that this is responsible for other occasional reports of early boot failure, and it does not hurt to add %esi to the clobbers.
Cc: H. Peter Anvin <hpa@zytor.com> Cc: Justin Forbes <jmforbes@linuxtx.org>
Signed-off-by: Michael K Johnson <johnsonm@rpath.com>
diff --git a/arch/x86/boot/memory.c b/arch/x86/boot/memory.c index 8c3c25f..fa85af7 100644 --- a/arch/x86/boot/memory.c +++ b/arch/x86/boot/memory.c @@ -27,13 +27,14 @@ static int detect_memory_e820(void) do { size = sizeof(struct e820entry); - /* Important: %edx is clobbered by some BIOSes, - so it must be either used for the error output + /* Important: %edx and %esi are clobbered by some BIOSes, + so they must be either used for the error output or explicitly marked clobbered. */ asm("int $0x15; setc %0" : "=d" (err), "+b" (next), "=a" (id), "+c" (size), "=m" (*desc) - : "D" (desc), "d" (SMAP), "a" (0xe820)); + : "D" (desc), "d" (SMAP), "a" (0xe820) + : "%esi"); /* BIOSes which terminate the chain with CF = 1 as opposed to %ebx = 0 don't always report the SMAP signature on
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