Re: [PATCH] tee: remove dead select from kconfig

[Arnd Bergmann]

On Wed, Jul 15, 2026, at 11:25, Julian Braha wrote:
> 'select' does not work on config options in a 'choice', so currently it is
> possible to enable QCOMTEE without QCOM_TZMEM_MODE_SHMBRIDGE.
>
> This patch removes the select.
>
> I've compile-tested this and found that it builds fine without
> QCOM_TZMEM_MODE_SHMBRIDGE, but I don't have the hardware to runtime test.
> Please advise if it would be better to make QCOM_TZMEM_MODE_SHMBRIDGE a
> dependency.
>
> This dead select was found by kconfirm, a static analysis tool for Kconfig.

Right, clearly something is wrong here.

> @@ -5,7 +5,6 @@ config QCOMTEE
>  	depends on ARCH_QCOM || COMPILE_TEST
>  	depends on !CPU_BIG_ENDIAN
>  	select QCOM_SCM
> -	select QCOM_TZMEM_MODE_SHMBRIDGE
>  	help

>From the implementation, my guess would be that QCOMTEE actually
requires QCOM_TZMEM_MODE_SHMBRIDGE and it only links successfully
because of the stub helpers added in 8aa1e3a6f0ff ("firmware:
qcom: tzmem: export shm_bridge create/delete").

If that is the case, we probably need a 'depends on
QCOM_TZMEM_MODE_SHMBRIDGE' here, and can remove the stub
functions.

It is also possible that the 'choice' itself is wrong, and
this should be detected at runtime. It is a rather odd Kconfig
option, as it sounds like only one of the two is correct on
a given hardware. The CONFIG_QCOM_TZMEM_MODE_SHMBRIDGE variant
contains runtime hardware detection, so it should actually
be safe to enable that anywhere. If this is true, we could
just turn the choice into a 'bool' symbol and remove the
generic case.

I've added a few more people to Cc that may know the correct
answer here.

     Arnd