Re: GGI Project Unhappy On Linux
H. Peter Anvin (hpa@transmeta.com)
28 Mar 1998 02:46:23 GMT
Followup to: <m1soo4cedq.fsf@flinx.npwt.net>
By author: ebiederm+eric@npwt.net (Eric W. Biederman)
In newsgroup: linux.dev.kernel
>
> 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.
>
That is true, you have to use cli()..sti() or something to make the
set index - write data or set index - read data atomic.
-hpa
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