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 > MEMFD_BASE_ADDRESS? > > 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 https://edk2.groups.io/g/devel/message/53747 cover.1580857303.git.thomas.lendacky@amd.com">http://mid.mail-archive.com/cover.1580857303.git.thomas.lendacky@amd.com carves out some more PCDs in the FDF file. Thanks! Laszlo -=-=-=-=-=-=-=-=-=-=-=- 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] -=-=-=-=-=-=-=-=-=-=-=-
