Re: Contribution to the Hurd on L4

[Marcus Brinkmann]

At Thu, 30 Dec 2004 19:51:17 +0100,
Matthieu Lemerre <address@hidden> wrote:
> Neither task nor deva was started for me. I recompiled a l4 kernel and
> it worked. (Maybe I was using the old patch for pistachio 0.2)

If your grub config is right, and deva is not started, then you should
look at using the latest pistachio as required in the README.  deva
does have a cheesy kbd driver which echoes kbd input, and ESC will
trigger int $3 to get you into the debugger if you enabled the trap in
the configuration of pistachio.  That should give you a hint if it is
running.

> It works well when I omit the   l4_msg_append_simple_string_item (msg, 
> string_item);
> line, but fail with the e field of the IPC error code set to 4
> otherwise. After a while of hard debugging session (I have to reboot,
> bochs won't run on my old PC), I decided to flood the mailing list a little 
> more :)
> 

By now you found problems in libl4, so I didn't review your code.  You
could try qemu btw, which works fine for me when I run it within a gdb
session (don't ask).

> I have some questions regarding the libl4 interface:
> 
> -How to create a new string item with the GNU interface? The
>  _L4_string_item function does not have a GNU "name".

Yes, it is missing.  Want to send in a patch?

> -What is the bug in _L4_msg_get_string_item?

Wish I could remember with certainty, but it may very well be that I
think that it possibly violates the strict aliasing rules of ISO C99.
Ie, the casts of &msg[] pointers to the string type has to be replaced
with explicit assignments to msg[] from .raw parts of the string item,
as I did for the other similar functions at some time.

I don't know if you are familiar with the strict aliasing rules, if
the above sounds like gibberish to you, let me know and I will
elaborate.

> But maybe I should post my messages to help-hurd? I don't want to
> flood the mailing list with uninterresting questions.

No, please keep going, excellent stuff.

Thanks,
Marcus