Re: [PATCH] Fix reloading GDT on ACPI S3 wakeup (fwd)

From: Pavel Machek
Date: Thu Apr 14 2005 - 15:39:21 EST


Hi!

> 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.
>

Actually x86-64 needs this, too. Any testers?
Pavel

--- clean/arch/x86_64/kernel/acpi/wakeup.S 2005-01-22 21:24:51.000000000 +0100
+++ linux/arch/x86_64/kernel/acpi/wakeup.S 2005-04-14 22:34:18.000000000 +0200
@@ -67,7 +67,7 @@
shll $4, %eax
addl $(gdta - wakeup_code), %eax
movl %eax, gdt_48a +2 - wakeup_code
- lgdt %ds:gdt_48a - wakeup_code # load gdt with whatever is
+ lgdtl %ds:gdt_48a - wakeup_code # load gdt with whatever is
# appropriate

movl $1, %eax # protected mode (PE) bit


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