On 2011-09-12 19:56, Chris Friesen wrote: > > Hi, > > I've been away a bit but I'm now coming back to this issue. > > Is it expected that the kvm-kmod modules will allow PCI device > assignment (aka VT-d) with older kernels? If so, then is there an > expectation for how far back it will be supported? I haven't seen a > clear statement of this anywhere, and I think David was interested in > this as well. In general, it is supposed to work, but there are likely more quirks and limitation than with a recent kernel. Example: pci_reset_function is not available for < 2.6.28, thus the assigned device may not work properly if the guest depends on a reset or after the VM ran through a reset or <who-knows>. You may also run into bugs/limitations of required kernel subsystems like the IOMMU layer that were fixed in newer kernels. kvm-kmod only addresses the kvm modules here. > > Looking at the instructions at > "http://www.linux-kvm.org/page/How_to_assign_devices_with_VT-d_in_KVM";, > step 4 is to unbind the device from the host using the "pci_stub" > functionality. That code was only added to mainline for 2.6.29-rc1, so > it seems like extra work will be needed for 2.6.28 and earlier. pci_stub is not strictly required if you manage your system in a way that all other "interested" drivers are kept away from the assigned device. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
