[Xen-users] RE: Another question about msi.

["Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>]

>-----Original Message-----
>From: Carsten Schiers [mailto:carsten@xxxxxxxxxx] 
>Sent: 2009年3月27日 16:53
>To: Jiang, Yunhong; xen-users
>Subject: AW: Another question about msi.
>
>Thanks, so I will give it a try. 
>
>In fact I never found someting in docs that say: don't use 
>shared-interrupt devices 
>in different domains. But you will find some hints in the 
>internet not to do so.

Yes, shared interrupt is much more complex, and may impact performance or even 
cause trouble sometimes, especially in some corner case. So if in a production 
environemnt, it is not a good idea to use it, I think. 

>
>I remeber something line an issue when shutting down a DomU 
>that includes one device, 
>that the other device doesn't work any longer, as the GSI is 
>disabled in Dom0. Might 
>be a bug. I never understand why it shouldn't work, as I think 
>the transfer from IRQ
>to event channel is done somewhere in Xen or Dom0.

Shared interrupt is quite tricky.

>
>My hope was that MSI will be much clearer, allowing me to use 
>the PCI slot, whilst
>the NICs are using MSI. Would be nice to put in another NIC or 
>TV or Fax or ...
>
>BR,
>Carsten.
>
>----- Originalnachricht -----
>Von: "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>
>Gesendet: Fre, 27.3.2009 02:21
>An: Carsten Schiers <carsten@xxxxxxxxxx> ; xen-users 
><xen-users@xxxxxxxxxxxxxxxxxxx>
>Betreff: RE: Another question about msi.
>
>
>
>>-----Original Message-----
>>From: Carsten Schiers [mailto:carsten@xxxxxxxxxx] 
>>Sent: 2009年3月27日 4:40
>>To: xen-users
>>Cc: Jiang, Yunhong
>>Subject: Another question about msi.
>>
>>Antoher question regarding MSI support.
>> 
>>When I have a motherboard where two PCIe slots and one PCI 
>>slot share an 
>>interrupt when using current
>>Xen and kernel with GSI, when I now use Xen 3.4-unstable and latest 
>>kernel, it will use the MSI (as the
>>Two PCIe slots are occupied by realtek NICs and their modules are MSI 
>>aware). Two different MSI show up 
>>in /proc/interrupts. 
>>
>>Does this now mean that I can pass-through the PCI slot into a 
>>pv DomU, 
>>because the GSI is now exclusively
>>used by the PCI slot (what I could not do before, as NICs shared GSI 
>>with the network cards)?
>
>I suspect even shared-interrupt devices can be assigned to 
>different guest.
>
>BTW, if a device can be assigned to a guest are determined by 
>many factor, like FLR support etc (at least for HVM domain).
>
>>
>>For your Info: Xen 3.3.1 and latest kernel will not work for me.
>>
>>Thanks,
>>Carsten.
>>
>>
>>
>>
>

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