What part of the article are you referring to and how exactly does it
improve performance for you?
- Nicolas
On 2016-05-21 11:42, Colin Godsey wrote:
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 <mailto:alex.l.william...@gmail.com>> wrote:
On Fri, May 20, 2016 at 11:38 AM, Nicolas Roy-Renaud
<nicolas.roy-renau...@ens.etsmtl.ca
<mailto: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
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