Re: Highmem on PPC?

On Tue, Feb 05, 2002 at 08:33:16PM +0100, Benjamin Herrenschmidt wrote:

quoted

I'm currently getting hard crashes on the dual 7410 with highmem.  Not
even the SMI starts xmon.  I'm not sure that it's a software bug,
which is why I'm getting the dual 7450.

Interesting. I have similar reports about dual 800s with 1.5G of RAM.
I don't personally have a machine with that much RAM, so it makes things
a bit difficult to debug. All I noticed so far is that
enabling interrupt distribution will cause occasional lockups on my
dual 7400 at work (not related to highmem). So if you plan to chase
this highmem bug, start by disabling that option to avoid mixing
problems.

I don't use interrupt distribution.

I triggered the absolute hard hang with my usual tests: 5 or 6 of the
following running in the background:

find /mnt/cdrom -exec cat {} \; > /dev/null 2>&1 &
find /usr -exec cat {} \; > /dev/null 2>&1 &

And a make -j8 zImage in the foreground.  I didn't even start the
flood ping before it hung. :)

Just in case it's a spinlock bug (who knows...) you may want to hack
the spinlock debug output to use the btext engine (basically #define
printf to xmon_printf in the spinlock code and hack xmon/start.c to
force use_screen).

This is actually over serial console, but I'll keep that in mind when
I get the apple.

And let me know if you find something ;)

:) You bet.  You're sure you're not seeing these hangs?  What are you
using, dual 7400 with 1 GB RAM?

-VAL

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quoted

And let me know if you find something ;)

:) You bet.  You're sure you're not seeing these hangs?  What are you
using, dual 7400 with 1 GB RAM?

I don't have a machine with enough RAM to do highmem. Actually, I could
probably test by hacking max_lowmem to 256Mb on my dual 7400, but it's
my work prod. machine so it's a bit tricky to do such tests on it.
It's not even supposed to run linux most of the time ;)

Ben.


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