LWP private support / TLS support

[Joerg Sonnenberger <joerg%britannica.bec.de@localhost>]

Hi all,
I've just committed the first major step to TLS support on NetBSD.
The M68K part is very rudimentary. It only covers the equivalent of
the lwp_setprivate/lwp_getprivate system calls. It doesn't provide a
fast access path yet. I am not aware of a CPU register that can be used
for this purpose. Contrary to the ARM port, which has the same problem,
M68K seems to be UP only. If that is the case, mapping a single fixed
page read-only into every (NetBSD) process would an efficient
implementation. Location could be passed down via ELF Auxillary Vector
or by sysctl. If SMP support is desired, a per-cpu mapping would be
needed for the same purpose. It would be great if someone with M68K
knowledge could pick this up and provide the necessary changes.
Feel free to contact me for questions of how this should be exposed to
userland and integrated with the rest.

Joerg