[Buildroot] [PATCH 1/1] boot/arm-trusted-firmware: use prebuilt BL33 images

Etienne Carriere etienne.carriere at linaro.org
Fri Aug 9 15:09:54 UTC 2019


Hello Thomas,

Thanks for the feedback.

> The proposed scheme is not ideal because for example the custom
> pre-built BL33 cannot be provided by another Buildroot package, as you
> cannot express the dependency.
>
> If all you're interested in is supporting OPTEE-OS, then I would
> recommend just add explicit support for it as an optional BL32 in ATF,
> without trying to be too flexible.
>
> If however you really want something that is very flexible, to allow
> both custom BL32 and BL33, then a possible solution is to create
> virtual packages: atf-bl32 and atf-bl33. optee_os would be a provider
> of atf-bl32, and U-Boot/Barebox could be providers of atf-bl33. This
> also allows custom packages in BR2_EXTERNAL, that package some custom
> BL32/BL33 to be providers of atf-bl32 or atf-bl33. This is of course
> more complicated to implement. Perhaps it is wise to wait and see if
> there really is a need for something like this.
>
> In the mean time, if what you want is just OPTEE-OS as BL32, keep it
> simple and add explicit handling for it in ATF.

I had UEFI in mind as it can be a BL33 boot stage used by ATF for
64bit Arm platforms. But it's not built from Buildroot, as pointed
from [1].
Yet I get your point about the need for clean dependency management in
a pristine Buildroot package.
Maybe I or someone can come up with a better proposal some day to address this.

Anyway, thanks again for all your feedback and detailed argumentation.

[1] https://github.com/buildroot/buildroot/blob/2019.05.x/board/aarch64-efi/readme.txt#L31

Regards,
etienne

>
> Thanks!
>
> Thomas
> --
> Thomas Petazzoni, CTO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com


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