On Tue, Sep 14, 2021 at 03:49:31AM +0000, Yao, Jiewen wrote: > I can explain why we prefer DQ instead of DD. > > You are right that current TD entrypoint is 32bit. However, we cannot predict > that is always TRUE for the future.
So a "save space in MEMFD" vs. "be future proof" tradeoff. > Back to 16 bit machine, we have entrypoint at F000:FFF0. But in 32bit mode we > removed 1M limitation and move entrypoint to below 4G. > There is no limitation that we move 64bit entrypoint above 4G for 64bit > machine. Any plans to actually do that? Defining an 64-bit entry point is a more than just using 64-bit addresses. For starters long mode requires paging being enabled. So a set of initial page tables is needed, and you possibly need to handle virtual vs. physical addresses. You also need to find a place above 4G where you can place the firmware without conflicts with something else. So I have my doubts that trying to make the struct future-proof will actually work out in practice. Or that we will actually need that anytime soon. take care, Gerd -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#80756): https://edk2.groups.io/g/devel/message/80756 Mute This Topic: https://groups.io/mt/85306660/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
