libpthread, libl4 fixes and additions

[Marcus Brinkmann]

Hi,

because commit logs are still defunct, here a few updates:

I checked in Neals libpthread from 2002, with small updates by Johan
from 2003.  Time is flying.

So, that pthread library is barely tested, in particular in relation
to the surrounding code.  The implementation of a mutex is not robust,
and there are probably zillions of other problems.  However, it's an
ideal playground to try out stuff and it is easy to hack it to do the
things we want.  This is why we are going to use it to get started.

Eventually, we want use NPTL in glibc properly, of course.  However,
even NPTL needs to be ported to L4, and the issues wrt mutexes etc are
all the same.  So there is not much of an overhead in using this
pthread implementation for now, rather the opposite: We can focus on
the L4 specific part of the code, and don't need to worry with all the
glibc specialities (for now).  This means we can use the pthread
interface in the servers we are writing very, very soon, and don't
need to hard-code l4_* all over the place.

I am now in the progress of testing the minimal features of libpthread
(thread creation from an L4 thread, mutex'es).  They don't need to be
perfect, but as soon as they work minimally, I can use them to test
the hurd capability stuff I have hacked on (which is far from
finished, but it is good to be able to test parts of it already, and
get some feel for how it performs).  Along the way, I will update the
pthread code to use the GNU libl4 interface, and change the GNU libl4
interface in turn.

There are also some other changes.  These changes imply that you must
use the most recent L4 version from CVS (pistachio).

So, nothing to get terribly excited about, but more things to come.

Thanks,
Marcus