Re: [Qemu-devel] [PATCH 0/3] hw: set irq without selecting INTx pin

[Marcel Apfelbaum <marcel.a@redhat.com>]

On Mon, 2013-09-30 at 13:10 +0300, Michael S. Tsirkin wrote:
> On Mon, Sep 30, 2013 at 12:43:20PM +0300, Marcel Apfelbaum wrote:
> > On Mon, 2013-09-30 at 12:14 +0300, Michael S. Tsirkin wrote:
> > > On Mon, Sep 30, 2013 at 11:02:06AM +0200, Paolo Bonzini wrote:
> > > > Il 30/09/2013 10:58, Michael S. Tsirkin ha scritto:
> > > > >>> > > As a next step, can we make pci_set_irq non-inline and make
> > > > >>> > > it call pci_irq_handler directly, and get rid of the irq field?
> > > > >> > What irq field? 
> > > > >     /* IRQ objects for the INTA-INTD pins.  */
> > > > >     qemu_irq *irq;
> > > > > 
> > > > 
> > > > That's still used by devices that use common code for PCI and sysbus
> > > > versions (e.g. USB OHCI and EHCI).
> > > > 
> > > > Paolo
> > > 
> > > Well this work wouldn't be complete without
> > > addressing them anyway.
> > > 
> > > These devices would have to create their own
> > > irq in pci-specific code, along the lines of:
> > 
> > This irq field is used also in places where pci_set_irq(PCIDevice dev, level)
> > can't infer the INTx:
> > - PCIExpress: qemu_set_irq(dev->irq[dev->exp.hpev_intx],dev->exp.hpev_notified);
> 
> Well the spec says, explicitly:
> 6.7.3.4.
>  Software Notification of Hot-Plug Events
> ...
> Note that all other interrupt sources within the same Function will
> assert the same virtual INTx wire
> when requesting service.
> 
> I read this to mean that this is a bug,
> and it should simply use pci_set_irq like all other
> devices.
Thanks!
That means that hpev_intx is not necessary at all.
By the way, aer_intx used by Advanced Error Reporting
is also unnecessary. (6.2.4.1.2 has the same note)

I will remove the above fields from PCIExpressDevice.
Marcel

> > - vmxnet3 device: qemu_set_irq(d->irq[int_idx], 1);
> > 
> > What approach should be used here?
> > 
> > Thanks,
> > Marcel
> > > - s->irq = dev->irq[3];
> > > + s->irq = qemu_allocate_irqs(pci_set_irq, dev, 1);
> > > 
> > > 
> > > If there's more than one device like this, we should add
> > > 
> > > /* Return an irq that calls pci_set_irq internally */
> > > qemu_irq *pci_allocate_irq(PCIDevice *);
> > > 
> > 
> >