Re: User Mode Mach?
> Many of these are the same benefits of a microkernel design. That is to
> say, if what you really want is to debug anything other than the device
> drivers or the scheduler, then you can already do that conveniently on the
> Hurd because filesystems, network stacks, etc, are not in the kernel
> anyway. The stable way to do this, that is similar in concept to
> "user-mode linux" is to run a "sub-Hurd", which is what we call it when you
> start a second set of Hurd servers on top of the Mach microkernel after a
> first Hurd is already booted. The Hurd's `boot' program facilitates doing
> this.
>
> If you really want a user-mode Mach, then it certainly could be done.
nanokernel | usermode mach | hurd | glibc | hello
We could just make the "nanokernel" a tiny chunk of code that saran wraps
the processor, write it entirely in asm, and have it export a -very-
limited set of functions (say, less than 10).
User-mode Mach would still need exceptional permissions, but the ghist of
it here is that it's userspace and protected.
It couldn't make the Hurd all that much slower than it already is :)
-MB
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