PCIe bridges resources disappearing with ACPI enabled.

[John Baldwin]

On Monday 27 October 2008 06:47:42 pm Serge Semenenko wrote:
> John Baldwin wrote:
> > On Saturday 25 October 2008 06:43:44 pm Alexander Motin wrote:
> >   
> >> Hi.
> >>
> >> I have spent whole day trying to investigate strange problem of my Acer
> >> TM6292 laptop (965GM+ICH8M). When booted with ACPI enabled, all three
> >> of PCIe-to-PCIe bridges appearing completely without I/O resources:
> >> pcib1: <ACPI PCI-PCI bridge> irq 17 at device 28.0 on pci0
> >> pcib1:   domain            0
> >> pcib1:   secondary bus     2
> >> pcib1:   subordinate bus   3
> >> pcib1:   I/O decode        0x0-0x0
> >> pcib1:   no prefetched decode
> >> ...
> >> At the same time, with ACPI disabled, resources are present. There are
> >> some different problem with IRQ in that case, but it is another
> >> question, not so interesting to me.
> >>
> >> I have tried both IO and memory mapped PCIe configuration registers 
> >> without success.
> >>
> >> I have made heavy digging trying to find where resources disappearing. I
> >> have even added debug printing inside pcireg_cfgwrite() and
> >> pciereg_cfgwrite() to trace if somebody erases it and found nothing.
> >> Nothing writes into that devices configuration registers.
> >>     
> >
> > The SMI handle could be clearing the BARs when ACPI is enabled for some 
> > reason.  Windows and Linux are smart enough to alloc resources for 
bridges, 
> > but FreeBSD isn't yet.
> >
> >   
> 
> Thanks for a good tip. Elimination of "Store (Zero, SMIC)" string from 
> ASL code has solved the problem.

That may not be a good solution though as there may be other things the SMI 
handler is doing to enable ACPI support that the OS is dependent on.

-- 
John Baldwin