Subject: Re: DDB vs Freeze
To: None <>
From: Michael C. Richardson <>
List: current-users
Date: 01/28/2000 11:29:44
>>>>> "Jason" == Jason Thorpe <> writes:

    Jason> On Thu, 27 Jan 2000 15:09:30 -0800 Hal Murray <>
    Jason> wrote:

    >> Would it be reasonable for the code that gets into DDB to get linked
    >> up with the display driver (if there is one on the box) and do
    >> something simple but conspicuous like video reversal to indicate that
    >> you are in DDB rather than hung?

    Jason> If we were able to do that on a PC, we'd be able to drop you back
    Jason> into text mode.

    Jason> The problem is that the kernel hasn't any idea how to get PC video
    Jason> cards into/out of graphics mode (because there are ... so many
    Jason> different ways...)

  My suggestion is that the X server (or svgalib, etc) that takes the
video card out of text mode should provide a recipe for putting it back
into text mode. A list of ports/values/memory locations that need to
be written to do the trick. 

  I don't know how long the list would be, but I can't imagine that it
is longer than 256 items or so. 

    >> or play a tune on the keyboard or ...  Anything to provide a strong
    >> hint that will indicate that the system isn't really hung.

    Jason> A tune on the keyboard certainly couldn't hurt, actually....

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