Generic S-mode RISC-V EDK2 payload?

[LekKit]

I see there is working support for RiscVVirt platform, which needs QEMU Virt + pflash device to run properly. However, there are other virtual machines without cfi_flash device emulation yet. Additionally, no actual RISC-V hardware has a cfi_flash device AFAIK.

Perhaps it makes sense to add another RiscVGeneric target which implements a generic S-mode payload to fw_jump OpenSBI stage, like U-Boot does for example?
I see there was something like that implemented fo FU540 board, which could be also booted on QEMU simply by passing a different -bios firmware: https://github.com/riscv-admin/riscv-uefi-edk2-docs?tab=readme-ov-file#edk2-risc-v-firmware-image-on-qemu.

Having a working upstread generic EDK2 S-mode payload would definitely help bring up support for other emulators like RVVM, and new actual hardware pieces.

[vlsunil]

qemu virt is the only platform supported in edk2 repo mainly to aid the CI testing including NV variables. Otherwise, edk2-platforms should be used for any new reference/real platforms. U540 is not a good example for your requirement since it has the design where EDK2 starts in M-mode directly instead of as a payload . That design is not flexible and hence any new platform should use payload approach itself. There are platforms already in edk2-platforms (ex: sg2042) which don't need flash like qemu virt but using payload design. They can be used as reference as well.

U540 need major cleanup and move to payload design. But currently, it is of low priority due to other tasks.

[LekKit]

Ah, thanks, it all makes much more sense now. I'll look at SG2042 platform soon, try to adapt it to my usecase and perhaps contribute a generic platform based on it if possible.

[vlsunil]

That will be great!. Thank you!