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

[Bernhard Beschow <shentey@xxxxxxxxx>]

Am 1. Juli 2023 11:58:57 UTC schrieb Mark Cave-Ayland 
<mark.cave-ayland@xxxxxxxxxxxx>:
>On 01/07/2023 10:53, Bernhard Beschow wrote:
>
>> 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.
>
>Certainly --enable-debug normally does the right thing when building QEMU. If 
>you want to double-check the compiler flags in use to see if anything from 
>CFLAGS/LDFLAGS is getting picked up, use "make V=1" after configure which 
>outputs the full command being used during the build rather than just the 
>summary.

--enable-debug does the right thing indeed. The error was on my side. Solved!

Thanks,
Bernhard
>
>
>ATB,
>
>Mark.
>