The HURD claims to be a group of servers which is currently running on the Mach microkernel but which could use another microkernel in the future.
Honestly 1) Its source is cluttered up with Mach-specific data structures/syscalls/library calls. 2) Even ordinary HURD applications that don't rely on the POSIX layer use Mach stuff. It is true that you can use POSIX (and pthreads in future) and stay portable but you can't fully utilize HURD features this way. And for all IPC servers (including HURD itself) this is not sufficient at all. I am interested if you really want HURD to be independent HIRD of Daemons or you are content with those mighty daemons being rather herd grazed by the Mach herder forever ;-) At this time it is not possible to port HURD to another microkernel without splitting its code base and this makes any porting efforts meaningless. L4-HURD seems to be dead for now because of this. HURD adopted many concepts from Mach. This should not be a problem (lets hope) but it must not depend on exact realization of these concepts (i.e. Mach API). HURD needs a thin layer (abstract wrapper) over Mach (this layer would be substantially thicker for other microkernels of course). This wrapper would only cover the portion of Mach services that HURD often uses. It could be just some sort of Mach emulation layer (with "neutral" function names - e.g. no "mach_xxx_yyy" but "mk_xxx_yyy") to some degree. This would be easy to implement for Mach and ports to other microkernels would become possible. Some Mach functions doesn't have to be included in this abstraction layer because they are already covered by POSIX or pthreads. And there is no big need for a full-featured microkernel abstraction library and for forbidding direct microkernel access - small part of application/server code can and will remain dependent (even just to exploit specific microkernel abilities). But it should not happen very often that you need to access microkernel functions directly from ordinary applications/servers. Microkernel-dependent code should be strictly separated from the rest so you know what is the subject of porting effort. All servers/libraries should place its bits of dependent code into special subdirectory (e.g. "trivfs/arch/mach") similar to Linux "arch" directory. What are your thoughts on this subject ? I think this issue should be solved before people start to write HURD-specific (non-POSIX) software. I am not able to do it myself as I am no HURD/Mach/L4/whatever expert. I would like to do some coding for HURD, no design. I have just begun studying the HURD so I hope i didn't blather too much nonsense and sorry for my broken eNgluSh ;-) ______________________________________________________________________ Jak poslat rukou psaný text na mail? Přece faxem Panasonic! http://www.panasonic.cz/redirect.html
