Re: [Qemu-devel] [PATCH 1/2] pci: Add pci_device_get_host_irq

[Michael S. Tsirkin]

On Fri, Jun 01, 2012 at 05:54:15PM +0200, Jan Kiszka wrote:
> On 2012-06-01 17:28, Michael S. Tsirkin wrote:
> >>> So I won't object to adding a new API but if we do
> >>> it properly this won't help compatibility :(
> >>
> >> It will as this API does not touch the parts that affect the vmstate
> >> (ie. semantics of irq_count won't change).
> > 
> > Yes but irq_count in vmstate is a bug. IMO even if we do
> > not change anything we should ignore irq_count on
> > load and recalculate it from what the devices supply.
> 
> I don't disagree. But this will only allow keeping backward migration
> support if we preserve the semantics of current map_irq somewhere - to
> keep the chance of calculating the legacy values for vmsave as well.
> 
> Jan

We don't need to preserve it, right? We can calculate it before
savevm.

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