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Re: [Qemu-devel] [Xen-devel] Re: [PATCH] xen: fix interrupt routing
From: |
Alexander Graf |
Subject: |
Re: [Qemu-devel] [Xen-devel] Re: [PATCH] xen: fix interrupt routing |
Date: |
Wed, 15 Jun 2011 18:54:30 +0200 |
Am 15.06.2011 um 18:34 schrieb Avi Kivity <address@hidden>:
> On 06/15/2011 11:24 AM, Alexander Graf wrote:
>> I'm actually not quite sure what exactly he's describing here. But if it's
>> bypassing the bus logic, it's not a normal PCI device :). Sure, there are
>> special case devices that also expose a PCI interface. But real PCI cards
>> that you plug in onto the PCI bus can't bypass the interrupt logic of the
>> bus, as the only interrupt wires they have go to the bus. And since the PCI
>> adapters we use in PC machines in Qemu are all non-special, guests can
>> possibly choke on this.
>>
>
> There actually is a special device in qemu - acpi power management is
> configured as a PCI device, but its interrupt is hard-wired to gsi 9 and is
> edge-triggered (so it can't share the irq line).
>
> I other devices that are special in this regard to also be part of the
> chipset, not devices you can plug into arbitrary slots.
Sure, platform devices can do that. Real PCI cards can not. Have you ever seen
an e1000 with direct mapped interrupt lines? :)
I admit though that we also emulate platform devices that happen to expose
themselves on the PCI bus. It's not common though and I wouldn't expect every
OS/driver to be happy about it.
Alex
>
- Re: [Qemu-devel] [PATCH] xen: fix interrupt routing, Alexander Graf, 2011/06/14
- Re: [Qemu-devel] [Xen-devel] Re: [PATCH] xen: fix interrupt routing, Ian Campbell, 2011/06/14
- Re: [Qemu-devel] [Xen-devel] Re: [PATCH] xen: fix interrupt routing, Alexander Graf, 2011/06/14
- Re: [Qemu-devel] [Xen-devel] Re: [PATCH] xen: fix interrupt routing, Stefano Stabellini, 2011/06/14
- Re: [Qemu-devel] [PATCH] xen: fix interrupt routing, Jan Kiszka, 2011/06/14
- Re: [Qemu-devel] [PATCH] xen: fix interrupt routing, Stefano Stabellini, 2011/06/14
- Re: [Qemu-devel] [PATCH] xen: fix interrupt routing, Alexander Graf, 2011/06/15
- Re: [Qemu-devel] [Xen-devel] Re: [PATCH] xen: fix interrupt routing, Avi Kivity, 2011/06/15
- Re: [Qemu-devel] [Xen-devel] Re: [PATCH] xen: fix interrupt routing,
Alexander Graf <=
- Re: [Qemu-devel] [Xen-devel] Re: [PATCH] xen: fix interrupt routing, Alexander Graf, 2011/06/15
- Re: [Qemu-devel] [Xen-devel] Re: [PATCH] xen: fix interrupt routing, Stefano Stabellini, 2011/06/15