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Commit 01522df3 authored by Michael K. Johnson's avatar Michael K. Johnson Committed by H. Peter Anvin
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x86, setup: mark %esi as clobbered in E820 BIOS call 



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.

-stable candidate patch.

Cc: Justin Forbes <jmforbes@linuxtx.org>
Signed-off-by: default avatarMichael K Johnson <johnsonm@rpath.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
Cc: stable@kernel.org
parent c8608d6b

arch/x86/boot/memory.c

+4 −3
Original line number Original line Diff line number Diff line
@@ -27,13 +27,14 @@ static int detect_memory_e820(void) 
	do {

	do {

		size = sizeof(struct e820entry);

		size = sizeof(struct e820entry);





		/* Important: %edx is clobbered by some BIOSes,

		/* Important: %edx and %esi are clobbered by some BIOSes,

		   so it must be either used for the error output

		   so they must be either used for the error output

		   or explicitly marked clobbered. */

		   or explicitly marked clobbered. */

		asm("int $0x15; setc %0"

		asm("int $0x15; setc %0"

		    : "=d" (err), "+b" (next), "=a" (id), "+c" (size),

		    : "=d" (err), "+b" (next), "=a" (id), "+c" (size),

		      "=m" (*desc)

		      "=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

		/* BIOSes which terminate the chain with CF = 1 as opposed

		   to %ebx = 0 don't always report the SMAP signature on

		   to %ebx = 0 don't always report the SMAP signature on