WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: [Xen-devel] Re: [PATCH] xen: fix interrupt routing

To: Avi Kivity <avi@xxxxxxxxxx>
Subject: Re: [Xen-devel] Re: [PATCH] xen: fix interrupt routing
From: Alexander Graf <agraf@xxxxxxx>
Date: Wed, 15 Jun 2011 18:54:30 +0200
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>, Jan Kiszka <jan.kiszka@xxxxxxxxxxx>, "qemu-devel@xxxxxxxxxx" <qemu-devel@xxxxxxxxxx>, Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>, Isaku Yamahata <yamahata@xxxxxxxxxxxxx>, Anthony Liguori <anthony@xxxxxxxxxxxxx>
Delivery-date: Wed, 15 Jun 2011 09:56:20 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <4DF8DF11.1030206@xxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <alpine.DEB.2.00.1105261645560.12963@kaball-desktop> <21A10B78-49E2-453B-8AE6-48155E2071B5@xxxxxxx> <alpine.DEB.2.00.1105311123210.12963@kaball-desktop> <68B936C0-E230-4B48-A274-CB875ED92D5E@xxxxxxx> <1308053820.17937.72.camel@xxxxxxxxxxxxxxxxxxxxxx> <1D2C3E16-193F-4EEC-B7EF-AE038B4F2EE9@xxxxxxx> <alpine.DEB.2.00.1106141344260.12963@kaball-desktop> <4DF77E8E.40806@xxxxxxxxxxx> <alpine.DEB.2.00.1106141658180.12963@kaball-desktop> <DCAB4C78-3A84-41F0-8074-3E2712F60EE4@xxxxxxx> <4DF8DF11.1030206@xxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Am 15.06.2011 um 18:34 schrieb Avi Kivity <avi@xxxxxxxxxx>:

> 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

> 

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel