[LinuxBIOS] MB1030 / 3036 VGA problems with IRQs

Stefan Reinauer stepan at coresystems.de
Tue May 16 14:08:20 CEST 2006

* Christian Sühs <chris at suehsi.de> [060516 16:54]:
> >pirq tables of factory bios are very often incomplete or wrong.
> >One reason is that pirq and mptable are not used by the OS 
> >when ACPI is active. (Well, talking Linux) So this is an untested 
> >(and usually unused) path. 
> ACPI is not enabled in the kernel.
> What about the bios parameters? There is a switch to enable/disable for 
> pnp os intalled. Eventually there are differences if I run getpir in 
> both cases? Or should I set the IRQs manually in the bios before I run 
> getpir.

Look at the hardware and write a valid pirq table.. getpir is a nice
tool but it starts out by utilizing a broken piece of software, the
factory bios. One entry in the pirq table for each device that gets an
interrupt and for each pci slot is needed.

Most factory bios versions explicitly allocate interrupts for the
existing hardware by writing to the PCI registers. 

LinuxBIOS does not do that, but instead provides the information to have
Linux do that. 

If the interrupts are already initialized by the bios, a broken pirq
table is not all too bad, except that its good for nothing except
forcing the kernel into certain code paths (no joke)


coresystems GmbH • Brahmsstr. 16 • D-79104 Freiburg i. Br.
      Tel.: +49 761 7668825 • Fax: +49 761 7664613
Email: info at coresystems.dehttp://www.coresystems.de/

More information about the coreboot mailing list