Re: X and VT-switching bug?

H. Peter Anvin (
13 Dec 1997 13:01:04 GMT

Followup to: <>
By author: teunis <>
In newsgroup:
> FWIW x86 hardware is broken by design (anything capable of VGA is broken.
> As is CGA, EGA, hercules-monochrome, ...). x86 graphics hardware is _NOT_
> designed for secure and/or multiuser environments.

I disagree -- VGA is not inherently broken (unless you count its
rather limited capabilities and random feature set as broken.) EGA
was (write-only registers), but IBM actually wised up on that one.

It is perfectly possible -- and not even very hard -- to query and
restore the complete state of a VGA card. Unfortunately, some
graphics chip manufacturers didn't carry this on. I am truly
surprised to hear there are chips you can't even force into a known
state without a bus reset -- whomever came up with that one should be
shot, tortured, and then *really* hurt... c'mon, folks, it ain't that
hard to give your thing a card-specific reset if you have to... *sigh*


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