Lots of polishing, organizational changes, bug fixes, error handling etc. are
introduced.
COPY and NEW space thread creation are allowed but not thoroughly tested yet. It
seems they will work best if the lib supports utcb virtual range management
through the mapping.
Now, we support thread trees which are spanning more than one level depth. Any
thread can create any number of threads provided that they are under the limits
which are enforced by the kernel.
Also with this commit, we have almost finished supporting SHARED space thread
creation in which stack and utcb space are allocated statically.
In order to do resource recycling we need a table structure. In the search of
one, we concluded that a task list will make things easier when we start adding
COPY and NEW space handling.
This commit is for utcb recycling. Now, it does not support thread trees more
than one level depth. Thus, to be able to test it, we preferred l4thread_destroy
instead of l4thread_exit.
UTCB support has beed added. It has the same drawback as in the stack support:
the area in question has to be already mapped-in.
There are also some minor fixes for the stack support and the utcb common helper
routines.
The difference between this thread library and the existing ones like pthreads
is the necessity of informing the library about the address range of the stack
and the l4 specific utcb. Utcb has not been supported yet. As for stack, there
is also a drawback: library does not support mapping. In other words, the stack
area in question has to be already mapped-in. Thus, for now we only support
threads sharing their address spaces: TC_SHARE_SPACE. In this respect, it is
very similar to pthreads.
