[Nouveau] kmmio dump log format

[Phillip Ezolt]

Pekka,

On 6/28/07, Pekka Paalanen <pq at iki.fi> wrote:
> On Wed, 27 Jun 2007 14:25:58 -0400
> "Phillip Ezolt" <phillipezolt at gmail.com> wrote:
>
> > Pekka,
> >
> > In your redesign of the binary dump format, could you add the ability
> > to store multiple PCs per sample? (ie, so that I can do backtraces (4
> > frames deep?) ) rather than just a single PC?
>
> The new format will be packet based, so it will be extendable. Yes, we
> can do this, I and Jeff just have to discuss how to do it exactly. And
> Jeff seems to be very busy nowadays.
>

That's great.  I know how the "very busy" thing goes.  I just wanted
to chip in my request if you were going to rework it anyway.

>
> > Since fglrx actually has useful symbols in the kernel module, I was
> > able to determine the meaning of some of the register accesses by
> > looking at the stack trace.  (It wasn't enough to just look at the PC,
> > since it was in some generic 'do_mmio' function... I needed the frame
> > above it.)   I would like to do this again for some of the other
> > registers that I don't know the meaning of yet..
>
> We can do it, I just hope you will not get any legal issues because of
> doing it. I do not think Nouveau would ever use PC/stack recording, it
> is a bit too deep into the gray area.
>

Well, this is the same information that would be printed during a
kernel oops, so it can't be THAT secretive.  Also, they export the
symbols+address, and there is no disassembly involved.

Anyway, to each his own. ;-)

> > BTW. I can send you the patch if you want, but it is very i386
> > specific & (if I remember) it requires framepointers.
>
> I would say that let's wait until the log format rework is done,
> because it will inflict changes also to the kernel side. And to be
> honest, I'd rather leave kernel stuff to other people. And my system is
> 64-bit.
>

Alright.  Cool.  I'll just sit tight, then.

> --
> Pekka "PQ" Paalanen
> http://www.iki.fi/pq/
>

Cheers,
--Phil