Re: 2.6.0-test6: APM unable to suspend (the 2.6.0-test2 saga continues)

[Russell King <rmk+lkml@arm.linux.org.uk>]

On Sun, Dec 28, 2003 at 05:46:22PM +0000, Russell King wrote:
> Alan Cox has shed some light on this problem.  He mentions that the
> x86 GDT/LDT stuff changed around 2.5.30, which is the time when others
> have also reported that their APM has stopped working.  I've not
> confirmed whether that is the case for me as well, but it seems to
> be highly likely.
> 
> I also asked Alan if there's the possibility of backing this out or
> making it configurable, but the answer seems to be a most definite
> no.  However, maybe Ingo can say otherwise?
> 
> This effectively means that people with laptops which do not work
> with 2.6 APM nor ACPI can expect their machines to be stuck with 2.4
> for the future, unless someone with the necessary knowledge sees this
> problem as important enough to solve.

A quick follow-up from a discussion I've just had with Andi Kleen...
Note that I know nothing about the x86 internals of LDT/GDT/APM stuff,
so I'm clutching at straws here...

Would it be possible to switch LDT/GDT to whatever the APM BIOS expects
just before calling the APM BIOS to suspend/hibernate, and restore them
to whatever Linux requires after the APM BIOS returns from resume?

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core