* Device assignment theoretical questions
@ 2009-07-18 15:05 Wolfgang Nothdurft
2009-07-23 10:03 ` Han, Weidong
0 siblings, 1 reply; 2+ messages in thread
From: Wolfgang Nothdurft @ 2009-07-18 15:05 UTC (permalink / raw)
To: kvm
Hi,
what limits does kvm have with device assignment and vt-d enabled.
- Is it possible to assign pci devices behind the same pci bridge to
different guests?
- Is there a limit how many devices can be assigned to one guest?
- What kind of cards work with the dma=none option?
Regards
Wolfgang
^ permalink raw reply [flat|nested] 2+ messages in thread
* RE: Device assignment theoretical questions
2009-07-18 15:05 Device assignment theoretical questions Wolfgang Nothdurft
@ 2009-07-23 10:03 ` Han, Weidong
0 siblings, 0 replies; 2+ messages in thread
From: Han, Weidong @ 2009-07-23 10:03 UTC (permalink / raw)
To: 'Wolfgang Nothdurft', 'kvm@vger.kernel.org'
Wolfgang Nothdurft wrote:
> Hi,
>
> what limits does kvm have with device assignment and vt-d enabled.
>
> - Is it possible to assign pci devices behind the same pci bridge to
> different guests?
For devices behind conventional PCI bridges, the source-id in the DMA requests is the requester-id of the bridge device. For devices behind PCI Express-to-PCI/PCI-X bridges, the source-id possibly is the source-id of the original PCI-X transaction or the source-id provided by the bridge. So devices behind these bridges can only be collectively assigned to a single guest.
> - Is there a limit how many devices can be assigned to one guest?
VT-d doesn't have the limitation. kvm guest supports 32 devices.
> - What kind of cards work with the dma=none option?
dma=none implements DMA remapping using software method. I think it needn't depend on device. You can refer to Amit's pv-dma tree for more information.
Regards,
Weidong
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2009-07-23 10:04 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2009-07-18 15:05 Device assignment theoretical questions Wolfgang Nothdurft
2009-07-23 10:03 ` Han, Weidong
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.