Re: [PATCH] arm64: Allow disabling of the compat vDSO

[Nick Desaulniers]

On Thu, Sep 26, 2019 at 12:47 AM Catalin Marinas
<catalin.marinas@xxxxxxx> wrote:
>
> On Thu, Sep 26, 2019 at 01:06:50AM +0100, Vincenzo Frascino wrote:
> > On 9/25/19 6:08 PM, Catalin Marinas wrote:
> > > On Wed, Sep 25, 2019 at 09:53:16AM -0700, Nick Desaulniers wrote:
> > >> On Wed, Sep 25, 2019 at 6:09 AM Catalin Marinas <catalin.marinas@xxxxxxx> wrote:
> > >>> Suggestions for future improvements of the compat vDSO handling:
> > >>>
> > >>> - replace the CROSS_COMPILE_COMPAT prefix with a full COMPATCC; maybe
> > >>>   check that it indeed produces 32-bit code
> >
> > CROSS_COMPILE_COMPAT is called like this for symmetry with CROSS_COMPILE.
>
> Actually, what gets in the way is the CONFIG_CROSS_COMPILE_COMPAT_VDSO.
> We can keep CROSS_COMPILE_COMPAT together with COMPATCC initialised to
> $(CROSS_COMPILE_COMPAT)gcc. When we will be able to build the compat
> vDSO with clang, we just pass COMPATCC=clang on the make line and the
> kernel Makefile will figure out the --target option from
> CROSS_COMPILE_COMPAT (see how CLANG_FLAGS is handled).
>
> If we stick only to env variables or make cmd line (without Kconfig) for
> the compiler name, we can add a COMPATCC_IS_CLANG in the Kconfig
> directly and simply not allow the enabling the COMPAT_VDSO if we don't
> have the right compiler. This saves us warnings during build.

Yes, I think this would be a nice approach.
-- 
Thanks,
~Nick Desaulniers