Re: [Qemu-devel] [PATCH] tests: vm: auto_install OpenBSD

["Daniel P. Berrangé" <berrange@redhat.com>]

On Fri, Aug 24, 2018 at 03:46:31PM +0100, Peter Maydell wrote:
> On 24 August 2018 at 15:43, Daniel P. Berrangé <berrange@redhat.com> wrote:
> > On Fri, Aug 24, 2018 at 10:36:30AM -0400, Brad Smith wrote:
> >> I very much appreciate the effort to bump up to 6.3 as I was going
> >> to suggest doing that at some point. But bumping up to 6.3 at the
> >> moment will fail with the configure script. We've switched from GCC 4.2
> >> to Clang. The TLS check will fail with Clang's emulated TLS. We've
> >> had a local patch for awhile to fix the test but I don't think it is
> >> appropriate to upstream as is.
> >>
> >> Index: configure
> >> --- configure.orig
> >> +++ configure
> >> @@ -1876,7 +1876,7 @@ static __thread int tls_var;
> >>  int main(void) { return tls_var; }
> >>  EOF
> >> -if ! compile_prog "-Werror" "" ; then
> >> +if ! compile_prog "-Werror" "-pthread" ; then
> >>      error_exit "Your compiler does not support the __thread specifier for " \
> >>       "Thread-Local Storage (TLS). Please upgrade to a version that does."
> >>  fi
> >
> > Later on in the configure script there's a check for pthreads that
> > sets $PTHREAD_LIB to the desired arg.
> >
> > Best is probably to move that check higher up, and then use $PTHREAD_LIB
> > as the argument to the compile_prog call you show.
> 
> Is emulated TLS a sufficiently complete/performant TLS
> implementation for our purposes?
> 
> (I think it would be better if OpenBSD just implemented real TLS
> like every other host OS we support.)

My reading of the situation is that OpenBSD *does* support real TLS,
but our configure script failed to detect that it supported it,
due to missing "-pthread" arg.

Regards,
Daniel
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