Porting GNU Hurd to L4
Table of Contents
Development can't start until some other things have been completed.
For further discussion, write to the mailing list.
OKUJI Yoshinori has compiled the differences between L4 and Mach on this page.
Why porting the Hurd to another microkernel?
- One of the design goals of GNU Hurd was to be platform (architecture, microkernel) independent.
This is NOT the case at the moment.
- GNU Mach runs only on IA32 systems.
- GNU Mach doesn't support SMP.
- There are L4 implementations for IA32, ARM, Alpha and MIPS.
- L4 is being actively developed.
- L4Ka (Pistachio) will,
and L4/Alpha already does support SMP.
- In the future, L4 will run on distributed systems, perhaps the Hurd will benefit from that.
- GNU Mach is BIG (more than 100 system calls). L4 is fast and small (7 system calls).
- Mach has built-in device drivers, that means a bug in a driver can crash the whole system.
- The Hurd hasn't ever been ported to another microkernel.
Porting it for the first time will help to be able to do that in the future.
The first discussions on the mailing list have shown that there it won't be easy to do the
port, one suggestion was to rewrite the Hurd servers from scratch.
- To do before starting the port:
- A pthreads implementation for both Mach and L4.
- Hurd must be ported to pthreads (instead of cthreads).
- A C library for L4.
- The Hurd is not that microkernel-independent as claimed in the past,
it makes use of many Mach-specific features.
- Mach and L4 are quite different.
- The L4 interface is not fix yet, there will still be changes in the future.
- There are no built-in device drivers. An interface for drivers is needed.
- Platform specs of the GNU toolchain have to be changed.
See this message.
GNU C Library
- Farid Haji wrote a patch for using Bochs to boot L4Ka, there is a page containing instructions how to use it.
- Microkernels and MK-based Systems
- Platform specific sites
There is no code yet...
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Updated: 18 March 2001 zeno