Problem installing the "nouveau" driver

Mike McCarty Mike.McCarty at sbcglobal.net
Wed Jun 30 11:25:58 PDT 2010


Simon Geard wrote:
> On Tue, 2010-06-29 at 10:25 -0500, alupu at verizon.net wrote:

You were ok up to here...

> The 80x25 mode you boot in is special in that regard, because that
> combination of pixels and fonts is implemented in the BIOS itself, as a
> standard feature going back 20 years. And being provided by the BIOS,
> it's not available if something else is driving the hardware.

That font is implemented in ROM inside the graphics controller, not
the BIOS. To get access to it, one simply has to command the controller
to use it. If one does that, the boot screen content usually magically
reappears, unless one also switches to a different RAM page for display,
or if some frame buffer mode was used during boot.

> An aside: One thing you might have noticed under the NVIDIA binaries. If
> you switch from X to a console, it switches back to 80x25, since those
> drivers are X only. When you switch back to X, they take over again, and
> have to work out what state the hardware is in - occasionally you see

Actually, they need to remember what state the controller was in.

> corruption (usually in OpenGL apps), where the drivers haven't gotten it
> right. I've once seen black and white patterns reminiscent of a text
> console appearing in textures, for example, as if the BIOS had put
> something into video memory, and NVIDIA hadn't cleared it out again.

That's certainly possible, and can be caused by the video processor
being in the right mode, but using the wrong RAM page.

> It's a driver bug when it happens, of course, but I mention it to
> illustrate the conflict between BIOS and OS driving the hardware.

Yep.

Mike
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