On Thu, 15 Dec 2016 21:01:19 +0000 Zir Blazer <zir_bla...@hotmail.com> wrote:
> > This guide still indicates support for 4th generation (aka > > Haswell), but I don't know how accurate it is: > > > > https://github.com/01org/gvt-linux/wiki/GVTg_Setup_Guide > > Probabily a typo or oversight. Here is a quote straight from one of the Intel > devs from less than a month ago on iGVT-g Mailing List: > https://lists.01.org/pipermail/igvt-g/2016-November/001024.html > > Q: Will Haswell ever be put back into the validation matrix and possibly > considered for KVM support? > A: Unfortunately, the answer is no. :( > KVMGT supported platform starts from Broadwell (including Broadwell). We have > no plan to add Haswell platform code into KVMGT because Broadwell GPU has big > difference with Haswell's. I had assumed Broadwell since that's where support for Universal Pass-Thru (UPT) mode starts for direct assigned IGD, but the setup guide got my hopes up. Darn. > > One of the advantages of the vfio mediated device interface is that API > > exposed to the user, and thus QEMU, is identical to a directly assigned > > device. Therefore AFAIK, there are no QEMU changes necessary for > > KVMGT. > As far that I recall, QEMU modifications were required because iGVT-g added a > lot of new invokation parameters, but I checked the new KVMGT Setup Guide you > linked, and it seems that they changed the procedure a bit. > > As of Sep 2016, according to near the end of this file: > https://01.org/igvt-g/blogs/wangbo85/2016/kvmgt-environment-setup-guide-using-gvt-g-installation-iso > ...in order to use iGVT-g in a VM, you had to invoke QEMU using these custom > parameters: > > -vgt > -vga vgt > -vgt_high_gm_sz 384 > -vgt_fence_sz 4 > -vgt_low_gm_sz 128 > > > On the guide you listed, here: > https://github.com/01org/gvt-linux/wiki/GVTg_Setup_Guide > ...instead, you use some command line parameters to create a vGPU in the > host, then invoke QEMU with -device vfio-pci as if you were doing Passthrough > but with a sysfsdev parameter pointing to the vGPU: > > -vga none > -device isa-vga > -device > vfio-pci,sysfsdev=/sys/bus/pci/devices/0000:00:02.0/894f3983-1a36-42b3-b52c-1024aca216be > > > I didn't followed what changes they did to get the iGVT-g support upstream, > but previously QEMU also needed a few tweaks to work with it. I suppose that > some logic that they used to do in their custom QEMU got moved into the > Kernel and thus it may work without further modifications, as you said. Prior to this summer Intel was on a very different path to enable KVMGT through QEMU. Earlier prototypes used a completely different architecture from what we have now, so I'm not surprised that you can find older guides with QEMU options that exist anymore. Thanks, Alex _______________________________________________ vfio-users mailing list vfio-users@redhat.com https://www.redhat.com/mailman/listinfo/vfio-users
