On 9/28/20 2:24 PM, Heinrich Schuchardt wrote: > On 28.09.20 19:15, Sean Anderson wrote: >> On 9/28/20 12:27 PM, Heinrich Schuchardt wrote: >>> On 28.09.20 18:08, Sean Anderson wrote: >>>> >From section 2.3.7 of the UEFI specification: >>>> >>>>> RISC-V UEFI will only be executed in machine mode. The machine mode has >>>>> the highest privilege and this mode is the only mandatory privilege level >>>>> for RISC-V platforms; all other privilege levels are optional depending >>>>> on the platform requirements. Machine mode is the first mode entered at >>>>> the power-on reset. This level is used in UEFI for low-level access to a >>>>> hardware platform. >>>> >>>> Signed-off-by: Sean Anderson <[email protected]> >>>> --- >>>> >>>> lib/efi_loader/Kconfig | 2 ++ >>>> 1 file changed, 2 insertions(+) >>>> >>>> diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig >>>> index bad1a29ba8..2197c84bf3 100644 >>>> --- a/lib/efi_loader/Kconfig >>>> +++ b/lib/efi_loader/Kconfig >>>> @@ -10,6 +10,8 @@ config EFI_LOADER >>>> depends on !EFI_STUB || !X86_64 || EFI_STUB_64BIT >>>> # We need EFI_STUB_32BIT to be set on x86_32 with EFI_STUB >>>> depends on !EFI_STUB || !X86 || X86_64 || EFI_STUB_32BIT >>>> + # RISC-V UEFI must run in machine mode >>>> + depends on !RISCV || RISCV_M_MODE >>>> default y if !ARM || SYS_CPU = armv7 || SYS_CPU = armv8 >>>> select LIB_UUID >>>> select HAVE_BLOCK_DEVICE >>>> >>> >>> Hello Sean, >>> >>> the specification is wrong. A change request has been made to correct >>> the specification. We should not change U-Boot here. >>> >>> See the discussion in this thread: >>> https://lists.linaro.org/pipermail/boot-architecture/2020-September/001481.html >>> >>> Best regards >>> >>> Heinrich >>> >> >> Thanks for linking that. I'm glad some of these issues are being addressed. >> However, I am concerned about your suggestion >> >>> * Don't trust the values of tp and gp when entered >>> from the payloads world. >> >> Because tp *must* be trusted in S-Mode... >> >> Of course, all this could be averted by adding an sbi_get_mhartid function... > > I thought only the secondary hart uses tp in U-Boot. > > Best regards > > Heinrich >
So UEFI is only ever ran on a single hart? I thought one of the advantages of UEFI was that it could initialize devices in parallel. --Sean
