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SubjectRe: [RFC] Reliable video POSTing on resume
On Sat, 05 Feb 2005 02:17:22 +0000, Matthew Garrett <> wrote:
> On laptops, it's frequently the case that c000:0003 will jump to a
> section of code that is no longer mapped into the address space.
> Instead, it's entirely possible that some other section of BIOS will be
> mapped there. The resulting behaviour is undefined, and can cause the
> hardware to hang.

I suspect the problem in that case is a compressed VBIOS. Some laptops
compress the VBIOS and the system BIOS into a single ROM and then
expand them at power on. Sounds like this is not happening on resume.
To get around the problem copy the image from C000:0 before suspend to
a place in preserved RAM where wakeup.S can find it and then copy it
back to C000:0 on resume. To test for this checksum C000:0 before
suspend and after and see if it has changed.

You can always do a simple test. If a program like vbios.vm86 or
vbetool can reset the card, then there is no reason wakeup.S shouldn't
be able to do it too if the environment is set up correctly.

Jon Smirl
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