Re: [PATCH v3 5/5] riscv: vdso: Implement __vdso_futex_robust_try_unlock()

[Nam Cao <namcao@linutronix.de>]

Thomas Weißschuh <thomas.weissschuh@linutronix.de> writes:
> Can it ever happen that the toolchain has differing zacas support between
> 32-bit and 64-bit? Then cpu_supports_zacas() may not be sufficient.

No idea. Probably not.

But if it does differ, we will get a clear compile-time error message
(unrecognized instruction or something like that). We can worry about it then.

> If it is guaranteed to be in sync I would prefer to reuse
> CONFIG_TOOLCHAIN_HAS_ZACAS instead of the cc-option check in the Makefile
> to make that clear and error out early if it should ever change.

I intend to apply Vivian's .option suggestion. That won't be required then.
>
> Also this assumes that compat vDSO alternative patching works.
> But this is not the case. My series [0] to implement it has not yet been
> applied. This revision is missing the note about this dependency.
>
> [0] https://lore.kernel.org/all/20260630-riscv-vdso32-alternative-v1-0-a32fd89b7b1c@linutronix.de/

Right, thanks.

> Could be :
>
> vdso-syms += __vdso_futex_robust_list$(BITS)_try_unlock

Wasn't aware that BITS exists, nice!

Nam