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Subject[patch 011/100] x86, setup: mark %esi as clobbered in E820 BIOS call
-stable review patch.  If anyone has any objections, please let us know.
From: Michael K. Johnson <>

upstream commit: 01522df346f846906eaf6ca57148641476209909

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 <>
Signed-off-by: Michael K Johnson <>
Signed-off-by: H. Peter Anvin <>
Signed-off-by: Chris Wright <>
arch/x86/boot/memory.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- 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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