Windows 10 forcing X2APIC: https://support.microsoft.com/en-us/kb/2303458
This helped a bunch for me at least on 4.4- I think there was some confusion on the correct way to signal the guest on what APIC to use, forcing this gave me much better %sys times. AFAIK it can also still be used with hyper-v APIC because that’s just the EOI para-virtualization. On Fri, May 20, 2016 at 2:28 PM Alex Williamson <alex.l.william...@gmail.com> wrote: > On Fri, May 20, 2016 at 11:38 AM, Nicolas Roy-Renaud < > nicolas.roy-renau...@ens.etsmtl.ca> wrote: > >> Did you have any issues with efifb or some other driver grabbing the gard >> before vfio-pci? What are your IOMMU groups like, which chard is your >> boot_vga, what script or method do you use to get vfio-pci to bind with >> your card, what's your kernel command line and what modules are included in >> your initramfs? >> >> I've struggled with getting my primary GPU to work correctly for a >> passthrough like this, and I ended up switching it up with the secondary >> because I simply couldn't get it to work properly (I'd keep getting >> something about "Invalid ROM contents") and I couldn't see my boot logs >> until the host driver finished loading. It's really inconvenient now >> becuase my motherboard is designed so that having a full-size GPU in the >> second PCIe slot blocks 4 SATA ports out of 6, so I need to have L-shaped >> cables in a bunch of places to make everything work properly. >> > > The boot VGA ROM is handled differently from other PCI ROMs in Linux, when > you read it you're actually reading a shadow copy of it placed at 0xc0000, > which has its roots back in the original IBM PC history. Execution of the > VGA ROM is allowed to modify this copy of the ROM image in memory. Thus > you're really not getting a pristine copy of the device ROM and it can > often lead to these invalid ROM contents messages. I wish we provided raw > access to the PCI option ROM in these cases as well. For now, if you do > have these sorts of invalid ROM messages, I would suggest that you at least > boot with the card as secondary, dump the ROM, then use that collected > image with the romfile= option rather than use the shadow copy. I had to > add some code to vfio to fix device IDs and checksums for IGD assignment > because of this, I don't know if there's any standard fixup we can do for > other vendors. Thanks, > > Alex > _______________________________________________ > vfio-users mailing list > vfio-users@redhat.com > https://www.redhat.com/mailman/listinfo/vfio-users >
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