Re: [edk2-devel] [BUG] Extremely slow boot times with CPU and GPU passthrough and host phys-bits > 40

["Gerd Hoffmann via groups.io" <kraxel=redhat.com@groups.io>]

On Thu, Nov 21, 2024 at 04:23:32PM -0800, mitchell.augustin via groups.io wrote:
> Thanks for the suggestions, Gerd.
> 
> > '-global ICH9-LPC.acpi-pci-hotplug-with-bridge-support=off'
> 
> Unfortunatly, this did not result in any change in boot time.
> 
> > '-cpu $name,host-phys-bits=on,host-phys-bits-limit=$bits'
> 
> -cpu host,host-phys-bits=on,host-phys-bits-limit=40 does result in the desired very fast boot time, but I get errors when I try to load the GPU driver:
> 
> NVRM: BAR0 is 0M @ 0x0 (PCI:0000:06:00.0)

OVMF scales the pcie root port bridge windows with the address space.

So you can try increase host-phys-bits-limit.  Values between 40 and 46
should have an effect.

The opt/ovmf/X-PciMmio64Mb setting already mentioned elsewhere in this
thread should also work with the dynamic mmio window.

> * *I ask this because I notice that when I disable host passthrough *(which works with my GPUs and results in a fast boot if `pci=realloc pci=nocrs` are used)* , my VM shows "Address sizes: 40 bits physical, 48 bits virtual", but when I use host passthrough and only override the physbits (which fails as described above), my VM shows "Address sizes: 40 bits physical, 57 bits virtual". (so I'm wondering if that could be a factor here.)*

It's 5-level paging support, and the qemu option name for that is la57
(-cpu $name,la57={on|off})

take care,
  Gerd



-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#120816): https://edk2.groups.io/g/devel/message/120816
Mute This Topic: https://groups.io/mt/109651206/7686176
Group Owner: devel+owner@edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [rebecca@openfw.io]
-=-=-=-=-=-=-=-=-=-=-=-