[Anna, can you fix your word-wrapping please? Your lines appear to be infinitely long which is most unpleasant to reply to] On Thu, Nov 06, 2008 at 05:38:16PM +0000, Fischer, Anna wrote: > > Where would the VF drivers have to be associated? On the "pci_dev" > > level or on a higher one? > > A VF appears to the Linux OS as a standard (full, additional) PCI > device. The driver is associated in the same way as for a normal PCI > device. Ideally, you would use SR-IOV devices on a virtualized system, > for example, using Xen. A VF can then be assigned to a guest domain as > a full PCI device. It's not clear thats the right solution. If the VF devices are _only_ going to be used by the guest, then arguably, we don't want to create pci_devs for them in the host. (I think it _is_ the right answer, but I want to make it clear there's multiple opinions on this). > > Will all drivers that want to bind to a "VF" device need to be > > rewritten? > > Currently, any vendor providing a SR-IOV device needs to provide a PF > driver and a VF driver that runs on their hardware. A VF driver does not > necessarily need to know much about SR-IOV but just run on the presented > PCI device. You might want to have a communication channel between PF > and VF driver though, for various reasons, if such a channel is not > provided in hardware. That is one model. Another model is to provide one driver that can handle both PF and VF devices. A third model is to provide, say, a Windows VF driver and a Xen PF driver and only support Windows-on-Xen. (This last would probably be an exercise in foot-shooting, but nevertheless, I've heard it mooted). > > Yeah, that's what I'm worried/curious about. Without seeing the code > > for such a driver, how can we properly evaluate if this infrastructure > > is the correct one and the proper way to do all of this? > > Yu's API allows a PF driver to register with the Linux PCI code and use > it to activate VFs and allocate their resources. The PF driver needs to > be modified to work with that API. While you can argue about how that API > is supposed to look like, it is clear that such an API is required in some > form. The PF driver needs to know when VFs are active as it might want to > allocate further (device-specific) resources to VFs or initiate further > (device-specific) configurations. While probably a lot of SR-IOV specific > code has to be in the PF driver, there is also support required from > the Linux PCI subsystem, which is to some extend provided by Yu's patches. Everyone agrees that some support is necessary. The question is exactly what it looks like. I must confess to not having reviewed this latest patch series yet -- I'm a little burned out on patch review. -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step." -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
