[LinuxBIOS] MB1030 / 3036 VGA: disabling 00:12:4

Christian Sühs chris at suehsi.de
Sat Apr 29 00:59:25 CEST 2006

Many thanks for that,

Goodrich,Steven schrieb:
> I've looked at the original BIOS source and the internal versions of the 
> documentation, and here's what I've determined:  As near as I can tell, 
> you cannot disable the PCI header for the device at 00:12:4.  The 
> original BIOS (written by others on the BIOS team here at AMD in 
> Colorado) virtualized the PCI headers via SMM code, and that header was 
> masked when internal graphics were disabled.  Without SMM code, you 
> cannot do the same thing.

Okay, First we have thought, that the enabled but not used device causes 
the trouble we have had at the beginning. At the moment it seems there 
is somewhere an other reason for our problems.
However, I will find it ;)

> Interesting info/notes:
> If you disable memory space via the PCI header (PCI header register 04, 
> bit 1 -- clear to zero), you should disable it somewhat.
> If the F4 Video Configuration trap bit (F0, Index 42h, bit 1) is set, 
> the system will generate SMIs when trying to access the PCI header 
> registers.  This should be clear for a non-SMM system.

Yeah, I have read that and it could be useful.

> I suppose you could special-case the device in your PCI scan/enumeration 
> code, but that is probably more kludgy than you'd like.  Could you 
> reduce the device's resource requirements to zero?

I think we could. It is shown, but not allocated at the moment, 
therefore it uses no resources.

regards chris

>     -- Steve G.
> *****Steve Goodrich* (_____Steven.Goodrich at amd.com_ 
> <mailto:Steven.Goodrich at amd.com>)
> Advanced Micro Devices, Inc.
> 1351 S. Sunset Street
> Mail Stop 83-36
> Longmont, CO  80501
> 303-774-5129    (fax: 303-774-5801)
> http://www.amd.com/embeddedprocessors

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