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

[Philippe Mathieu-Daudé]

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)