From: Juerg Billeter This patch - based on http://marc.theaimsgroup.com/?l=linux-kernel&m=110055503031009&w=2 - makes ACPI S3 wakeup work for me on a ThinkPad T40p laptop with a SMP kernel. Without it only UP kernels work. I've been using the patch for three months now without any issues. The ACPI resume code currently uses a real-mode 16-bit lgdt instruction to reload the GDT. This only restores the lower 24 bits of the GDT base address. In recent SMP kernels, the GDT seems to have moved out of the lower 16 megs, thereby causing the ACPI resume to fail -- an invalid GDT was being loaded. Signed-off-by: Juerg Billeter Signed-off-by: Andrew Morton --- 25-akpm/arch/i386/kernel/acpi/wakeup.S | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff -puN arch/i386/kernel/acpi/wakeup.S~acpi-fix-reloading-gdt-on-acpi-s3-wakeup arch/i386/kernel/acpi/wakeup.S --- 25/arch/i386/kernel/acpi/wakeup.S~acpi-fix-reloading-gdt-on-acpi-s3-wakeup Fri Apr 8 16:43:55 2005 +++ 25-akpm/arch/i386/kernel/acpi/wakeup.S Fri Apr 8 16:43:55 2005 @@ -74,8 +74,9 @@ wakeup_code: movw %ax,%fs movw $0x0e00 + 'i', %fs:(0x12) - # need a gdt - lgdt real_save_gdt - wakeup_code + # need a gdt -- use lgdtl to force 32-bit operands, in case + # the GDT is located past 16 megabytes + lgdtl real_save_gdt - wakeup_code movl real_save_cr0 - wakeup_code, %eax movl %eax, %cr0 _