Virtualization - Oct 2022 - [GIT PULL] virtio: fixes, features

On Wed, Oct 12, 2022 at 11:06:54PM +0200, Arnd Bergmann
wrote:
> On Wed, Oct 12, 2022, at 7:22 PM, Linus Torvalds wrote:
> >
> > The NO_IRQ thing is mainly actually defined by a few drivers that just
> > never got converted to the proper world order, and even then you can
> > see the confusion (ie some drivers use "-1", others use
"0", and yet
> > others use "((unsigned int)(-1)".
> 
> The last time I looked at removing it for arch/arm/, one problem was
> that there were a number of platforms using IRQ 0 as a valid number.
> We have converted most of them in the meantime, leaving now only
> mach-rpc and mach-footbridge. For the other platforms, we just
> renumbered all interrupts to add one, but footbridge apparently
> relies on hardcoded ISA interrupts in device drivers. For rpc,
> it looks like IRQ 0 (printer) already wouldn't work, and it
> looks like there was never a driver referencing it either.

Do these two boxes even have pci?
> I see that openrisc and parisc also still define NO_IRQ to -1, but at
> least openrisc already relies on 0 being the invalid IRQ (from
> CONFIG_IRQ_DOMAIN), probably parisc as well.
> 
>      Arnd

On Thu, Oct 13, 2022, at 12:08 AM, Michael S. Tsirkin
wrote:
> On Wed, Oct 12, 2022 at 11:06:54PM +0200, Arnd Bergmann wrote:
>> On Wed, Oct 12, 2022, at 7:22 PM, Linus Torvalds wrote:
>> >
>> > The NO_IRQ thing is mainly actually defined by a few drivers that
just
>> > never got converted to the proper world order, and even then you
can
>> > see the confusion (ie some drivers use "-1", others use
"0", and yet
>> > others use "((unsigned int)(-1)".
>> 
>> The last time I looked at removing it for arch/arm/, one problem was
>> that there were a number of platforms using IRQ 0 as a valid number.
>> We have converted most of them in the meantime, leaving now only
>> mach-rpc and mach-footbridge. For the other platforms, we just
>> renumbered all interrupts to add one, but footbridge apparently
>> relies on hardcoded ISA interrupts in device drivers. For rpc,
>> it looks like IRQ 0 (printer) already wouldn't work, and it
>> looks like there was never a driver referencing it either.
>
> Do these two boxes even have pci?
Footbridge/netwinder has PCI and PC-style ISA on-board devices
(floppy, ps2 mouse/keyboard, parport, soundblaster, ...), RiscPC
has neither.

    Arnd