[PATCH v5 0/4] Add system-wide tunables

[DJ Delorie]

> One thing I forgot to ask, currently only the tests that need the rseq 
> tunable disabled use GLIBC_TUNABLES to explictly set the value because 
> we expect the default to always be enabled.
>
> Since the default could now be disabled by a system-wide policy, should 
> I add GLIBC_TUNABLES to the environment of all rseq tests like this:
>
> tst-rseq-nptl-ENV = GLIBC_TUNABLES=glibc.pthread.rseq=1
>
> Or would that be considered overzealous?

Given your concerns about non-overridable settings, I think a check
inside the test to ensure the tunable is set the way the test expects,
and UNSUPPORTED if not, should be sufficient.

If (it's a big if) developers find their machines are usually in a
non-standard overridable configuration due to system-wide tunables they
have no control over...  we can revisit this then ;-)