> Subject: Re: [PATCH 0/16 v6] PCI: Linux kernel SR-IOV support > > On Thu, Nov 06, 2008 at 05:38:16PM +0000, Fischer, Anna wrote: > > > On Thu, Nov 06, 2008 at 08:41:53AM -0800, H L wrote: > > > > I have not modified any existing drivers, but instead I threw > > > together > > > > a bare-bones module enabling me to make a call to > pci_iov_register() > > > > and then poke at an SR-IOV adapter's /sys entries for which no > driver > > > > was loaded. > > > > > > > > It appears from my perusal thus far that drivers using these new > > > > SR-IOV patches will require modification; i.e. the driver > associated > > > > with the Physical Function (PF) will be required to make the > > > > pci_iov_register() call along with the requisite notify() > function. > > > > Essentially this suggests to me a model for the PF driver to > perform > > > > any "global actions" or setup on behalf of VFs before enabling > them > > > > after which VF drivers could be associated. > > > > > > 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 that "second" part that I'm worried about. How is that going to > happen? Do you have any patches that show this kind of "assignment"? That depends on your setup. Using Xen, you could assign the VF to a guest domain like any other PCI device, e.g. using PCI pass-through. For VMware, KVM, there are standard ways to do that, too. I currently don't see why SR-IOV devices would need any specific, non-standard mechanism for device assignment. > > > 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. > > Are there any such drivers available yet? I don't know. > > 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. > > Agreed, but what does that channel look like in Linux? > > I have some ideas of what I think it should look like, but if people > already have code, I'd love to see that as well. At this point I would guess that this code is vendor specific, as are the drivers. The issue I see is that most likely drivers will run in different environments, for example, in Xen the PF driver runs in a driver domain while a VF driver runs in a guest VM. So a communication channel would need to be either Xen specific, or vendor specific. Also, a guest using the VF might run Windows while the PF might be controlled under Linux. Anna -- 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
