Re: SMRAM sizes on large hosts

[Gerd Hoffmann <kraxel@redhat.com>]

On Di, 2017-05-02 at 20:49 +0000, Kinney, Michael D wrote:
> Laszlo,
> 
> Is it possible to add more TSEG sizes to the Q35 board?

qemu implements what physical q35 support.  The extended smram register
has two bits for the tseg size, three out of the four values are used
(for 1, 2, 8 MB sizes).  "11" is reserved in the specs.  We could use
"11" to implement a bigger tseg.  Current code sets the tseg size to
zero for "11".  Alternatively we could add some qemu-specific register.

When implementing this in qemu we will have to do it runtime-switchable,
for backward compatibility with older qemu versions.  So ideally
firmware would detect somehow whenever qemu supports a bigger tseg or
not and adapt at runtime.  If edk2 can't do this we would need two edk2
builds ...

cheers,
  Gerd