Re: [musl] [RFC] removing __NR_clock_gettime / SYS_clock_gettime

[Szabolcs Nagy <nsz@port70.net>]

* Rich Felker <dalias@libc.org> [2020-01-19 13:53:34 -0500]:
> On Sun, Jan 19, 2020 at 07:42:26PM +0100, Szabolcs Nagy wrote:
> > * Rich Felker <dalias@libc.org> [2020-01-19 13:16:43 -0500]:
> > > On Sun, Jan 19, 2020 at 06:51:17PM +0100, Szabolcs Nagy wrote:
> > > > i think you should build gcc with --enable-libstdcxx-time so
> > > > it does not try to do raw syscalls (which is bad on 64bit
> > > > targets too, not just for time64, i thought distros already
> > > > do this or patch out that entire thing)
> > > 
> > > It does raw syscalls with that as I understand it. You need =rt to
> > > make it do the right thing.
> > 
> > --enable-libstdcxx-time is default in mcm since
> > 
> > commit 0291cc44eee410270a97efb6258394c1f1f8352a
> > Commit:     Rich Felker <dalias@aerifal.cx>
> > CommitDate: 2016-05-06 18:37:09 +0000
> > 
> > and the libstdc++ i built with that only has SYS_futex
> > syscalls in it on all targets.
> > 
> > now i see that alpine libstdc++ has a raw clock_gettime
> > syscall in it too, alpine should fix that.
> 
> Oh, the --enable-libstdcxx-time we already had was sufficient? I
> thought --enable-libstdcxx-time and --enable-libstdcxx-time=rt were
> different. Latest commit message may be nonsense then... :/

  --enable-libstdcxx-time

is the same as

  --enable-libstdcxx-time=yes

which does proper configure checks,

  --enable-libstdcxx-time=rt

also checks -lrt which is not needed on musl,
but harmless (i guess it's an option so by
default libstdc++ avoids the -lrt dependency).

the default is =auto which hard-codes some
nonsense based on glibc version, we can fix
that for gcc-11 and them musl works without
magic options.