Re: [Qemu-devel] [PATCH 2/4] pci: Add generic PCIe host bridge

[Peter Maydell]

On 12 January 2015 at 21:06, Alexander Graf <address@hidden> wrote:
>
>
> On 12.01.15 21:08, Peter Maydell wrote:
>> On 12 January 2015 at 17:38, Alexander Graf <address@hidden> wrote:
>>> I'd prefer to keep things as easy as we humanly can for now. Then add
>>> MSI. And if we then realize that we still need 4 rather than 1 shared
>>> interrupt lines we can still change it :)
>>
>> Except that that would be a breaking change, so I would prefer
>> to think ahead where possible; at some point there will come
>> a time when we really can't make breaking changes to this
>> board any more...
>
> Works for me, then we stay at a single interrupt line. The only reason
> we have 4 in PCI is that back in the day you could have non-sharing PCI
> devices that were essentially ISA ones.

Well, also your typical small system probably doesn't have more
than 4 PCI slots and so 4 IRQs is enough to give them each one.
Most small VMs probably won't have more than four PCI devices
either...

-- PMM