Re: [PATCH v3 00/18] hw/ide: Untangle ISA/PCI abuses of ide_init_ioport()

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 3/3/23 08:46, Mark Cave-Ayland wrote:
> On 03/03/2023 06:58, David Woodhouse wrote:
> 
>> On 2 March 2023 22:40:40 GMT, "Philippe Mathieu-Daudé" 
>> <philmd@linaro.org> wrote:
>>> Since v2: rebased
>>>
>>> I'm posting this series as it to not block Bernhard's PIIX
>>> cleanup work. I don't have code change planned, but eventually
>>> reword / improve commit descriptions.
>>>
>>> Tested commit after commit to be sure it is bisectable. Sadly
>>> this was before Zoltan & Thomas report a problem with commit
>>> bb98e0f59c ("hw/isa/vt82c686: Remove intermediate IRQ forwarder").
>>
>> However much I stare at the partial revert which fixes it, I just 
>> cannot believe that the change could make any difference at all. 
>> There's got to be something weird going on there.
>>
>> I was going to ask if the level mode for the PIT made any difference, 
>> but this is the output IRQ from the PIT to the CPU itself so I don't 
>> see how it would.
>>
>> Would like to see a report with tracing from pic_update_irq, the CPU 
>> interrupt "handler" and the intermediate IRQ handler. With the 
>> intermediate present and without it. To compare the two.
> 
> I suspect it's related to the removal of the allocation of the qemu_irq: 
> qdev gpios work by adding a child IRQ object to the device, so it could 
> be possible that something in the gpio internals isn't being updated 
> correctly when the value is overwritten directly.
> 
> Is the problem picked up when running a binary built with 
> --enable-sanitizers? That's normally quite good at detecting this kind 
> of issue.

No ASan warning. However I see (before/after bb98e0f59c):

qemu-system-ppc: pc87312: unsupported device reconfiguration (0f 11 00)
qemu-system-ppc: pc87312: unsupported device reconfiguration (0f 11 84)
qemu-system-ppc: pc87312: unsupported device reconfiguration (09 01 84)