Re: Console handling (was: Re: Let's vote for PnP on 2.2)

Albert D. Cahalan (
Thu, 11 Dec 1997 01:47:39 -0500 (EST)

H. Peter Anvin writes:

>>> 1. Make the kernel know how to reset the video card to a known state.
>> You can go from a known state to a known state.
>> You can go from any state to an unknown state -- useless.
>> Sorry, you can't get to a known state from an unknown state.
> Sure you can. It's pretty common to do so. In fact, whenever
> you initialize hardware, this is usually exactly what you do.

I'd expect you to know better. Video hardware on the PC has
severe problems. If you can reach a known state, then you
are already in a known state or in a trivial unknown state.

If you can just initialize hardware, then explain why none
of the following can reset my video board:

SVGA app
"cold" BIOS reboot from Linux
Windows NT startup

Sometimes the front panel reset button fails to reset the video!

What works for you does not work for people with different hardware.
People like to say "log in and run restoretextmode". Nope, that won't
work -- even if it did though, it is quite gross.

The only way to avoid a crashed console is to simply avoid it.
Meaning: the system must always be aware of the video registers.
There is no recovery once the board crashes.