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<p>What part of the article are you referring to and how exactly
does it improve performance for you?</p>
<p>- Nicolas<br>
</p>
<div class="moz-cite-prefix">On 2016-05-21 11:42, Colin Godsey
wrote:<br>
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cite="mid:CAExLznd9Gi_c3zKDccECN2mFJe=AYiQ-+z_soWyQJ=UKt=6xLA@mail.gmail.com"
type="cite">
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<div dir="ltr">Windows 10 forcing X2APIC: <a
moz-do-not-send="true"
href="https://support.microsoft.com/en-us/kb/2303458"><a class="moz-txt-link-freetext" href="https://support.microsoft.com/en-us/kb/2303458">https://support.microsoft.com/en-us/kb/2303458</a></a>
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<div>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. </div>
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<div dir="ltr">On Fri, May 20, 2016 at 2:28 PM Alex Williamson
<<a moz-do-not-send="true"
href="mailto:alex.l.williamson@gmail.com">alex.l.williamson@gmail.com</a>>
wrote:<br>
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<div class="gmail_quote">On Fri, May 20, 2016 at 11:38 AM,
Nicolas Roy-Renaud <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:nicolas.roy-renaud.1@ens.etsmtl.ca"
target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:nicolas.roy-renaud.1@ens.etsmtl.ca">nicolas.roy-renaud.1@ens.etsmtl.ca</a></a>></span>
wrote:<br>
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<p>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?</p>
<p>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 "<code>Invalid
ROM contents</code>") 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.</p>
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<div>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,</div>
<div><br>
</div>
<div>Alex</div>
</div>
</div>
</div>
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