UEFI: Make architecture generic

[kallisti5]

UEFI needs to be reworked to build for non-x86 platforms. Recent u-boot's support .efi binary booting and would let us leverage u-boot's framebuffer in our haiku_loader. (reducing the need for hacked in early SOC hardware drivers for framebuffers and other devices haiku_loader needs). This would also let us consolidate boot loader target platforms... and help us have *real* drivers attached to and FDT bus in the kernel. (we would only need early uart drivers for debugging)

​https://www.cnx-software.com/2016/08/11/u-boot-now-supports-uefi-on-32-bit-and-64-bit-arm-platforms/

'bootefi' is the u-boot command to load an efi binary.

BOOTARM.EFI is the default boot choice for ARM platforms (kind of like BOOTX64.EFI is on x86_64)

Jessicah has some EFI rework in-flight (making the compiled x86 loader build both BIOS and UEFI loaders) that is a blocker to beginning this.

[korli]

What's the status here?

[pulkomandy]

I think there is still some arch-specific code that needs to be written for ARM and RISC-V, to hand over the MMU configuration to the kernel. But the setup for this is mostly in place and it's just a matter of filling in the platform specific parts?

[X512]

What's the status here?

Well, ARM and RISC-V haiku_loader.efi can compile, run and show boot menu. I think that ticket can be closed. The rest is implementing arch-specific part that is out of scope of this ticket.

[kallisti5]

This one is indeed resolved. I finished splitting the x86-only bootloader into architecture agnostic pieces a while ago.