Re: [PATCH v2] piix: fix regression during unplug in Xen HVM domUs

[Bernhard Beschow <shentey@xxxxxxxxx>]

Am 30. Juni 2023 08:48:02 UTC schrieb Paolo Bonzini <pbonzini@xxxxxxxxxx>:
>Il mer 28 giu 2023, 13:28 Bernhard Beschow <shentey@xxxxxxxxx> ha scritto:
>
>>
>>
>> Am 27. Juni 2023 12:07:40 UTC schrieb Olaf Hering <olaf@xxxxxxxxx>:
>> >Tue, 27 Jun 2023 10:12:50 +0000 Bernhard Beschow <shentey@xxxxxxxxx>:
>> >
>> >> The BAR is a 32 bit register whose default value is 0x00000001. I think
>> what's supposed to happen here is a pci_set_long() rather than a
>> pci_set_byte().
>> >
>> >Indeed, the u32 at that address changes from c121 to c101 with the
>> current code.
>>
>> Neat! Would you mind sending a patch fixing the BMIBA register to be reset
>> as 32 bit?
>>
>
>I think we should also check why writing the command register is not
>disabling the BAR as well.

So IIUC the BMIBA register is managed internally by QEMU's PCI code and we 
shouldn't have to mess with the register at all. We should actually remove the 
explicit reset of BMIBA, correct?

I've tried debugging the PCI code when working on the VIA IDE controller to 
understand it better. But despite QEMU being compiled with --enable-debug it 
seemd to be compiled with -O2 still, making debugging quite hard. I'm not sure 
if any compile flags leak into my build environment though.

Best regards,
Bernhard 
>
>Paolo
>
>
>> Best regards,
>> Bernhard
>> >
>> >Olaf
>>
>>