From: Tian Kevin Register %ebx serves as the "global offset table base register" for position-independent code. For absolute code, %ebx serves as a local register and has no specified role in the function calling sequence. In either case, a function must preserve the register value for the caller. acpi_copy_wakeup_routine overrides %ebx without saving it, this may corrupt the called data. Kevin found that most time the value of Sx is saved in %esi, however sometimes compiler also uses %ebx. When this happens, suspends fails since sleep value in ebx is changed by acpi_copy_wakeup_routine. The same funtion in X86_64 doesn't have this problem. Signed-off-by: Zhang Rui Looks-okay-to: Pavel Machek Signed-off-by: Rafael J. Wysocki Cc: Len Brown Cc: Andi Kleen Cc: Andrew Morton Signed-off-by: Andrew Morton --- arch/i386/kernel/acpi/wakeup.S | 2 ++ 1 files changed, 2 insertions(+) diff -puN arch/i386/kernel/acpi/wakeup.S~acpi-preserve-the-ebx-value-in-acpi_copy_wakeup_routine arch/i386/kernel/acpi/wakeup.S --- a/arch/i386/kernel/acpi/wakeup.S~acpi-preserve-the-ebx-value-in-acpi_copy_wakeup_routine +++ a/arch/i386/kernel/acpi/wakeup.S @@ -230,6 +230,7 @@ bogus_magic: # ENTRY(acpi_copy_wakeup_routine) + pushl %ebx sgdt saved_gdt sidt saved_idt sldt saved_ldt @@ -263,6 +264,7 @@ ENTRY(acpi_copy_wakeup_routine) movl %edx, video_flags - wakeup_start (%eax) movl $0x12345678, real_magic - wakeup_start (%eax) movl $0x12345678, saved_magic + popl %ebx ret save_registers: _