libports is a pretty good approximation of what we (the Hurd developers) think an IPC system ought to provide for server writers. It is certainly an open question as to how much is done in the microkernel's IPC system and how much is done in a user-level library. We do have strong opinions about the guarantees that should be provided, and have designed the Hurd around these assumptions (such as that no-senders notifications are guaranteed to be delivered soon when a task and all its send rights get destroyed, and this cannot be broken by any user-level action). (When I was working on the now-dead Fluke microkernel at the University of Utah, which had an IPC system somewhere in between Mach and L4 but much closer to L4 in its simplicity, we implemented a libports-like abstraction layer with the same essential properties as Hurd's libports on top of the much simpler microkernel abstractions. Of course that work was never really finished and research on that microkernel was abandoned before it was entirely usable.)
People keep saying they think the Hurd is "deeply wedded" to Mach IPC. I think all those people are just not really looking at the fundamentals of the Hurd code. Yes, we use MiG RPC presentations and Mach port operations. But aside from syntax that is trivial to change, we have a fairly small number of dependencies on Mach's idiosyncratic IPC features (like send-once rights and disconnected RPC). We have always been opening to redesigning parts of Hurd implementation to fit better with different IPC systems. Noone has ever gotten specific about what they want to do. I'm not sure that I'm on the l4-hurd list, so perhaps there has been some discussion there that I haven't seen. But every time someone posts to bug-hurd with their opinion about the Hurd's relationship to Mach, they speak in completely vague general terms and never present anything concrete about the details of the IPC system they'd like to work with, how they would adapt the Hurd to use it, and what the problems might be. As to your specific question, I can't imagine that anything you might call "L4Mach" would be a worthwhile thing to do from a Hurd perspective. But I am only guessing what you really have in mind, since you have not been at all specific. _______________________________________________ Bug-hurd mailing list [EMAIL PROTECTED] http://mail.gnu.org/mailman/listinfo/bug-hurd
