Re: 8xx MMU Table Walk Base (was Re: kernel crashes at InstructionTLBMiss )

Murray Jensen wrote:

On Mon, 05 Jun 2000 16:37:55 -0400, Dan Malek [off-list ref] writes:

...

quoted

After reading your diatribe

Diatribe? Hmm.. Sorry, I didn't mean to offend you - I thought I was being
reasonably clear, and definitely polite.

...

quoted

Finally, lots of bugs associated with porting to new hardware manifest
themselves as "problems" in any VM related function.  Since many people
don't understand the subtle interactions of all of these functions (as
evidenced by your message) you become convinced the problem is associated
with this complexity and fail to unravel the clues to the real cause.

I don't think I deserve this sort of belittling. Treating potential
contributors in this way can only have a negative effect on open
source development.

Murray,
please - hang in there.  We need more people like you.
Cut Dan some slack - he appears to be a genius at programming,
but maybe is a little short on people skills.  He means no harm,
but calls them as he sees them.  And as in baseball, not everyone
always agrees with the umpire.  :)
(At least; this is the impression
I've gathered in the relatively short time I've made his acquaintance
and have been reading this list).

quoted

some silicon
bug not understood,

I included my chip revision above. It appears to be a C1 revision chip.

quoted

or prototype hardware not working correctly.

Definitely.

quoted

There are lots of products and systems in development running this software,
so you have to approach this generic software from the assumption that
it is first likely to be working.

I did. I said I was intrigued as to why this problem only affected me. And
once I make the described change, the "generic software" works for me also
(at least an older revision works - current revisions still crash, something
to do with the memory allocation stuff, I believe).

As I said in my previous message, I suspect something else I am doing is
triggering this bug (that much is obvious), but there are two possibilities:
either I am doing something wrong in my local changes, or the "generic
software" has a bug which does not show up in anyone else's implementation. I
was wondering whether the latter was the case (I wasn't blaming anyone, I was
excited that maybe I had discovered a long existing hidden fault in the
software, that may explain some mysterious failure modes, that someone else
might be getting - other developers may then post, saying "yeah, that would
explain my problem, blah blah", and so the discussion goes on. Upon searching
the archives, I found that a similar problem had been discussed for the 2.2.x
kernels, so maybe the fix or fixes didn't make their way into the 2.[34].x
kernels. I don't know, anything is possible, that's why we have these
discussion groups).

Murray,
as far as I know - you are maybe the only one running 2.3.x on
a powerpc.  Most of the kernels that one can find lying about
are 2.2.x (13/14? Can't remember at the moment).

I, as well as others, definitely want to see 2.3.x or 2.4.0 running
on an embedded powerpc.

...

Again, apologies for not providing enough information in my message - I made
assumptions I shouldn't have. Obviously, on my first post I should have been
completely anal, because no-one knows me from a bar of soap. I can then start
to be less exacting after I have been around for a while.

Everyone enjoys sarcasm... :)  (Don't they?)

quoted

Where did you get the sources? What
patches did you apply?  What are your hardware details?  What
modifications did you make?

See above.

quoted

As for 2.4.xx, the 8xx still doesn't work correctly.  However, I
discovered it failed to work after the 403 additions, so I am now
learning about the 403 in an effort to make everything live happily
together again.

It was my feeling that the problems were to do with the new memory allocation
stuff introduced a couple of months ago.

quoted

Note, this has nothing to do with M_TWB......

I know. Now that we have gotten past treating me like a dill, please can you
re-read my original message and see if I am making any sense at all? I would
very much appreciate some insights and even constructive criticism. Cheers!
                                                                Murray...

PS: I haven't contributed the Cogent platform changes yet, because I wasn't
happy that I had done everything properly. This was really my first foray
into taking part in the Linux/PPC embedded development community - I can't
say it has been particularly successful (despite my good feelings about
contributing a small fix a couple of days ago). I will try not to be too
discouraged.

That's the spirit!

	-Dan	(A different one).

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