PCIe bridges resources disappearing with ACPI enabled.

[John Baldwin]

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.

-- 
John Baldwin