PCIe bridges resources disappearing with ACPI enabled.

[Serge Semenenko]

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.