Hi Andrew,

On 02/14/20 04:11, Andrew Fish via Groups.Io wrote:
> I'm trying to understand the constraints around the value used with 
> The reason I'm asking is I've been asked to remove firmware from using lower 
> memory addresses in the low 0x800000 range as it is taking up too many ASLR 
> bits in low memory VMs or some such. 
> At least on my OVMF config that seems to be PcdOvmfLockBoxStorageBase and 
> PcdOvmfPeiMemFvBase. It is easy enough to move MEMFD_BASE_ADDRESS to a much 
> higher address, but I'm not sure if there are any restrictions to the 
> addresses I can use?

TBH I've never researched moving around MEMFD_BASE_ADDRESS. As I stated
earlier, the exact value shouldn't really matter; what matters (i.e.
what various parts of OVMF platform code rely on) is the relative order
of "magic" areas (PCDs etc). We tend to use ASSERT()s to catch problems
in this area, but the coverage may not be complete. So best I can
suggest is, please experiment and see what breaks. (Test S3
suspend/resume too.)

BTW Tom Lendacky's in-progress series

[edk2-devel] [PATCH v4 00/40] SEV-ES guest support

carves out some more PCDs in the FDF file.


Groups.io Links: You receive all messages sent to this group.

View/Reply Online (#54456): https://edk2.groups.io/g/devel/message/54456
Mute This Topic: https://groups.io/mt/71261334/21656
Group Owner: devel+ow...@edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub  [arch...@mail-archive.com]

Reply via email to