[OpenBIOS] Re: [fb-d] closer ...

Jeff Garzik jgarzik at mandrakesoft.com
Wed May 3 18:41:01 CEST 2000

Ronald G Minnich wrote:
> On Wed, 3 May 2000, Jeff Garzik wrote:
> > For linuxbios/freebios, simply avoiding the Cirrus video BIOS init
> > should be sufficient I would think.  (though make sure to disable the
> > Cirrus's PCI MMIO and I/O regions)
> hmmm, I may disable the bios from probing that slot.
> This will soon be of no concern, since I am just about ready to turn the
> Intel bios off again ...

Various bits of advice:

* Video may be a red herring.  It seems more simple to me to disable ALL
video, and get serial console working.

* From reading the PCI spec, it seems like two passes are needed over
each PCI bus and device.  The first pass disables all devices, while at
the same time reading their address space requirements.  The second pass
enables each device, with the correct I/O and MMIO region settings. 
Note special cases like two VGA devices on the PCI bus need to be
handled by disabled the non-primary VGA device.

* If you run the video BIOS, everything gets easier!  You can simply use
vgacon and forget about other special consoles like sercon or fbdev.  It
is not a daunting as it seems, to run the video BIOS.  The procedure is
simple, and clearly detailed in the PCI spec I sent you.  I can help
too.  We eventually need to do this anyway.

* If you haven't already done so, run the Intel BIOS, get a fully copy
of the PCI config registers for -every- device, and then compare with
the results after running LinuxBIOS.  There may be something obvious you
are not setting up.  In my experience, comparing register dumps between
known good and devel code outputs are invaluable.


Jeff Garzik              | Nothing cures insomnia like the
Building 1024            | realization that it's time to get up.
MandrakeSoft, Inc.       |        -- random fortune
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