Re: [edk2-devel] [PATCH v5 4/5] Ovmf/PlatformPei: Use host-provided GPA end if available

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

On Mon, Apr 25, 2022 at 11:43:49PM +0200, Ojeda Leon, Nicolas via groups.io wrote:
> Read the "hardware-info" item from fw-cfg to extract specifications
> of PCI host bridges and analyze the 64-bit apertures of them to
> find out the highest 64-bit MMIO address required which determines
> the address space required by the guest, and, consequently, the
> FirstNonAddress used to calculate size of physical addresses.

Is there some way to (a) figure ovmf runs on aws, and (b) figure what
the physical address space is?

IIRC I've mentioned this before:  The reason for this FirstNonAddress
logic is that ovmf tries to be very conservative because when running on
qemu 'pc' and 'q35' machine types ovmf simply can't figure reliable how
much address space it actually has.

With qemu 'microvm' machine type this is not the case so standard cpuid
can be used instead:

https://edk2.groups.io/g/devel/message/89260?p=%2C%2C%2C20%2C0%2C0%2C0%3A%3Arecentpostdate%2Fsticky%2C%2CmPhysMemAddressWidth%2C20%2C2%2C0%2C90681717

So if using PlatformAddressWidthFromCpuid() as-is or something simliar
is an option this series could be simplified.  I think you don't need
to parse hardware-info in PEI then ...

(keeping the series as-is is fine with me too).

take care,
  Gerd