From: Tian Kevin <kevin.tian@xxxxxxxxx> 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 <rui.zhang@xxxxxxxxx> --- arch/i386/kernel/acpi/wakeup.S | 2 ++ 1 files changed, 2 insertions(+) Index: linux-2.6.22-rc3/arch/i386/kernel/acpi/wakeup.S =================================================================== --- linux-2.6.22-rc3.orig/arch/i386/kernel/acpi/wakeup.S 2007-05-31 17:23:56.000000000 +0800 +++ linux-2.6.22-rc3/arch/i386/kernel/acpi/wakeup.S 2007-05-31 17:24:08.000000000 +0800 @@ -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: - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
