Hi Ilias, On Mon, Jul 31, 2023 at 12:38:16PM +0300, Ilias Apalodimas wrote: > > > > > ... > > > > > Changelog: > > > > > =============== > > > > > > > > > > v17: > > > > > > > > > > * show a debug message rather than an error when FF-A is not detected > > > > [snip] > > > > > diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig > > > > > index c5835e6ef6..8fbadb9201 100644 > > > > > --- a/lib/efi_loader/Kconfig > > > > > +++ b/lib/efi_loader/Kconfig > > > > > @@ -55,13 +55,53 @@ config EFI_VARIABLE_FILE_STORE > > > > > stored as file /ubootefi.var on the EFI system partition. > > > > > > > > > > config EFI_MM_COMM_TEE > > > > > - bool "UEFI variables storage service via OP-TEE" > > > > > - depends on OPTEE > > > > > + bool "UEFI variables storage service via the trusted world" > > > > > + depends on OPTEE && ARM_FFA_TRANSPORT > > > > > > > > You didn't get my changes in here however. If you can do EFI_MM_COMM_TEE > > > > without ARM_FFA_TRANSPORT (as lx2160ardb_tfa_stmm_defconfig does) then > > > > you don't make this option depend on . If FF-A is only > > > > for use here, you make FF-A depend on this, and the FF-A specific > > > > variable depend on ARM_FFA_TRANSPORT. > > > > > > Abdellatif hinted at what's going on here. When I added this Kconfig > > > option to lx2160 FF-A wasn't implemented yet. > > > > The defconfig has existed since May 2020, which is when you added > > EFI_MM_COMM_TEE itself too. So I think it's that no one did the check I > > did until now and saw this series was disabling what was on the other > > platform. > > > > > Since FF-A isn't a new > > > communication mechanism but builds upon the existing SMCs to build an > > > easier API, I asked Abdellatif to hide this complexity. > > > We had two options, either make Kconfig options for either FF-A or the > > > traditional SMCs and remove the dependencies, or piggyback on FF-As > > > discovery mechanism and make the choice at runtime. The latter has a > > > small impact on code size, but imho makes developers' life a lot > > > easier. > > > > I'm not sure how much you can do a run-time option here since you're > > setting a bunch of default values for FF-A to 0 in Kconfig. If we're > > supposed to be able to get them at run time, we shouldn't need a Kconfig > > option at all. I'm also not sure how valid a use case it is where we > > won't know at build time what the rest of the firmware stack supports > > here. > > > > That's a fair point. FF-A in theory has APIs to discover memory. > Abdellatif, why do we need the Kconfigs for shared memory on FF-A?
The statically carved out MM shared buffer address, size and offset cannot be discovered by FF-A ABIs. The MM communication driver in U-Boot could allocate the buffer and share it with the MM SP but we do not implement that support currently in either U-Boot or UEFI. Simon suggested we use build configs to set the buffer address, size and offset since we don't want a DT node for the MM firmware. Kind regards Abdellatif
