Attention is currently required from: Arthur Heymans, Julius Werner, Jérémy Compostella, Kapil Porwal, Subrata Banik.
Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/81960?usp=email )
Change subject: arch/x86: Enable long mode entry into payload for x86_64 support ......................................................................
Patch Set 2:
(1 comment)
Patchset:
PS2: Subrata, please slow down. It's not just about implementing it and making it work. coreboot and the payload should be independent and interchangeable. If you want to create a 64-bit payload that can't be loaded by a current core- boot (or one from the release branches?) for no obvious reason, that's ok, but then you don't have to do it upstream. I would rather see it upstream, though. Adding a 64-bit ABI and handover is something we have to do anyway, for X86S. So any effort in that direction would be really appreciated, as long as we don't unnecessarily sarcifice compatibility.
The last handover convention worked for what? 20 years, maybe? Please see that as a goal for a 64-bit version. We should design and discuss something that can last 20 years without binary incompatibilities. And then implement it. In the mean time, you can use the old convention as long as your CPU supports protected mode.
Beside strengthening the ecosystem, compatibility is also good for other reasons. For instance, when someone debugs a regression and doesn't know if the problem is in the payload or in coreboot. In the past it was usually possible to try a new coreboot with an old payload build and vice versa.