[PATCH] S390: Influence hwcaps/stfle via GLIBC_TUNABLES.

[Florian Weimer]

* Stefan Liebler via Libc-alpha:

> This patch enables the option to influence hwcaps and stfle bits used
> by the s390 specific ifunc-resolvers.  The currently x86-specific
> tunable glibc.cpu.hwcaps is also used on s390x to achieve the task. In
> addition the user can also set a CPU arch-level like z13 instead of
> single HWCAP and STFLE features.
>
> Note that the tunable only handles the features which are really used
> in the IFUNC-resolvers.  All others are ignored as the values are only
> used inside glibc.  Thus we can influence:
> - HWCAP_S390_VXRS (z13)
> - HWCAP_S390_VXRS_EXT (z14)
> - HWCAP_S390_VXRS_EXT2 (z15)
> - STFLE_MIE3 (z15)
>
> The influenced hwcap/stfle-bits are stored in the s390-specific
> cpu_features struct which also contains reserved fields for future
> usage.
>
> The ifunc-resolvers and users of stfle bits are adjusted to use the
> information from cpu_features struct.
>
> On 31bit, the ELF_MACHINE_IRELATIVE macro is now also defined.
> Otherwise the new ifunc-resolvers segfaults as they depend on
> the not yet processed_rtld_global_ro@GLIBC_PRIVATE relocation.
> ---

I think you are updating all the right places.  You should probably push
this as the hardware maintainer.

Thanks,
Florian