Marcus Brinkmann <Marcus.Brinkmann <at> ruhr-uni-bochum.de>
2002-08-01 16:16:00 GMT
On Thu, Aug 01, 2002 at 06:26:07AM -0400, Roland McGrath wrote:
> > Certainly, however, as using the current infrastructure will require
> > more than a few changes, I thought it might make sense to just rewrite
> > it right now.
> Not really. I don't think your changes for L4 will need to be that extensive.
The changes with pthreads and the IPC model are independent, but they are
not just search and replace. Many changes are of syntactical nature, but
some are not, and there are also a couple of changes that are not just
search and replace but touch a lot of code.
In general, the goal is not to provide a full Mach emulation on L4, but to
tighten the requirements, in particular in the IPC structure. The reason
is not really to accomodate the design of L4, but to make the Hurd more
flexible, faster and more robust on platforms which allow that (Mach
doesn't ;). It might not be strictly necessary to change as much in the
Hurd to get it running on L4, but by reconsidering some of the assumptions
in the Hurd we can get huge benefits, and it's a good time to do it along
with the port, instead of afterwards.
I have followed Neal's work on L4 from the early beginning as good as I
could, and I think he is on the right track with those changes. It's too
early though to say if we can really keep the same Hurd code base for Mach
and L4 feasibly, in particular if it is worth the effort to write the
wrappers around Mach that would be needed to do that.
I have not given any details here, Neal will do this as soon as he feels
comfortable about that, and you probably don't have the time to dig into
them right now anyway. Some details are already available on the l4hurd