Re: [edk2-devel] [PATCH v1] OvmfPkg/PlatformInitLib: Don't override user specified PciMmio64Size

["Gerd Hoffmann" <kraxel@redhat.com>]

  Hi,

> > Strictly speaking you don't care that much about the size of the mmio
> > window, but where it gets placed.  Moving it to the end of the vcpu
> > address space is what breaks your use case in case the iommu address
> > space happens to be too small for that.
> Right, the crux of the problem is indeed the placement of the window
> and not the size. Given this, do you see any problem if the mmio window
> were to be placed at the lower end of the address space?

That might still not work because OVMF scales the window size with the
address space.

> Or, do you think
> ensuring that PhysMemAddressWidth = <IOMMU address width>
> automatically via Qemu/OVMF like Laszlo suggested is a better solution
> for this problem?

The best temporary stop gap IMHO is using 

  -cpu host-phys-bits=on,host-phys-bits-limit=<iommu-address-bits>

Side note: The qemu master branch has a precompiled seabios version
which also does iommu window scaling and will need the same treatment.

How to solve that long-term should be discussed on the qemu-devel list.

take care,
  Gerd



-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#110835): https://edk2.groups.io/g/devel/message/110835
Mute This Topic: https://groups.io/mt/102359124/7686176
Group Owner: devel+owner@edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [rebecca@openfw.io]
-=-=-=-=-=-=-=-=-=-=-=-