Re: Getting Started with Hurd-L4

[Marcus Brinkmann]

At Wed, 20 Oct 2004 19:55:46 +0100,
Sam Mason <address@hidden> wrote:
> Everything seemed to run OK in Bochs; I can put in some printfs and
> get output where I expect.  I've had a look at the TODO list and
> it all looks suitably low level!  I was wondering how much of it
> needs to be done before the more normal userland stuff starts to get
> written (by this I don't mean I want a shell, that's obviously going
> to be a while) like working out a prototype initalisation procedure.

Well, I will write a smallish task server any day now, which should be
good enough to create new tasks and allocate threads.  The physmem
server definitely needs more than the current dummy container,
although it turns out good enoough to run the task server and allocate
some anonymous memory (with a frightening dumb interface).

Then we need some fake/dummy device access server that let's you at
least have some minimal console device and a memory-based backing
store (ram disk made from a file in an archive in a grub module).
That's another couple of days easy hacking.

At that point, user level stuff can start (porting the C library, etc).

For real usability, much more work is needed of course.  In
particular, we need to create RPC stubs from an IDL (but _hurdish_ RPC
which means tight integration with the C library, and that's quite a
bummer).  Well, and much more.

> Is this all pretty much dictated by the existing Hurd artcheture,
> or have we got a reasonably clean slate to work from.

It's only dictated as much as we want to port the Hurd to it, so, we
have to provide the right primitives.  But as you can read in the doc/
document, it's quite radically different from Mach.

We are not trying to port the Hurd with minimal changes, so we feel
free to deal in the Hurd as much as needed, and that is quite a lot on
the surface, but surprisingly little on the overall design (not
surprising to the original designers of the Hurd, of course :).

It sounds like you are not scared of technical details.  I'd recommend
to read the design notes in the doc/hurd-on-l4.pdf document.  It
contains lots of those.  The TODO list is just the "working set" for
things to keep track of so they don't get lost.  The real stuff is in
our brains and in that document.  Ask questions, you'll need the answers ;)

Thanks,
Marcus