This basically means to get rid of sysdeps/mach/hurd/bits/libc-tsd.h (and thus the _HURD_THREADVAR_*/_hurd_threadvar_location interface), and directly use __thread instead.

IRC, freenode, #hurd, 2011-10-23:

<tschwinge> youpi: If we want to replace threadvars with TLS, there is one
  problem: the threadvars interface is publically exported:
  /usr/include/hurd/threadvar.h.
<tschwinge> youpi: But I am somewhat inclined to say that the only user of
  this is libthreads/libpthread.  Do you think differently?
<youpi> tschwinge: that's very probable
<youpi> so I think we can just drop it
<youpi> (people should use TLS anyway)

libpthread set stack size.

After this has been done, probably the whole __libc_tsd_* stuff can be dropped altogether, and __thread directly be used in glibc.