Re: [PATCH v3] AArch64: Add ifunc masking tunable

Hi Yury,

> The 'glibc.cpu.hwcaps' tunable is documented in the Glibc manual with
> this note:
>
>  This tunable is specific to i386, x86-64, s390x, powerpc and
>  loongarch.
>
> Now in this patch we are adding support for aarch64 but in a way that
> does not follow what is documented for other targets. This might result
> in confusion. Maybe we should add a comment to the manual that this
> tunable is partially supported on aarch64 but only allows to turn off
> some hwcaps and only those that don't affect security?

I'm not sure what you mean - it uses the exact same infrastructure, callbacks
etc. As for all targets, what settings are supported is target specific, including
what hwcap settings could be changed, enabled or disabled. In all cases
unsupported features are silently ignored. So what is different here?

>> +      if (tunable_str_comma_strcmp_cte (&n, "midr"))
>
> Should this (and similar values below) be '-midr' with the '-' used to
> make sure we only support disabling?

No, that's not how it works.

Cheers,
Wilco