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SubjectRe: GGI Project Unhappy On Linux
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>>>>> "HA" == H Peter Anvin <hpa@transmeta.com> writes:

>> As Alan Cox has stated, and as I know from personal experience[1]: you can
>> go from a known video state to a known video state, and you can go from a
>> known video state to an unknown (i.e., garbage) video state. You cannot,
>> short of resetting the card (which typically takes a reboot), go from an
>> unknown state to a known state. It simply doesn't work that way. Why?
>> Because the people who designed the VGA video hardware were idiots (IMHO).
>> That's why kernel-arbitrated video mode changing is needed, and that's what
>> KGI is. As Varg pointed out so eloquently, KGI is a leetle teeny tiny
>> piece of GGI that needs to be in the kernel. The rest doesn't.
>>

HA> Actually, the people who designed VGA were actually very careful to
HA> *not* make this mistake (that had previously been made in EGA);
HA> unfortunately, some of the people that copied and extended their
HA> design weren't that careful.

They were close except the index registers while resettable are not
readable. So you can rest it from a unknown state but you can 100%
reliably multitask access to the card.

Eric

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