[Crash-utility] Increase of NR_CPUS on IA64

[Bernhard Walle]

* Dave Anderson <anderson at redhat.com> [2007-10-19 18:23]:
> Bernhard Walle wrote:
>> * Bernhard Walle <bwalle at suse.de> [2007-10-19 17:24]:
>>> The solution for that problem is to calculate the number of CPUs for
>>> IA64 at runtime. The 2nd patch implements this, and also reads the
>>> registers from the LKCD dump header instead of guessing on the stack.
>>> This fixes a problem here -- unfortunately, I don't still have that
>>> dump to provide further details.
>> I forget to attach the 2nd patch ;)
>
> At this point I've lost most insights into the LKCD code.
> The ia64 pt_regs hardwiring bothers me, mainly because there have
> been changes to its definition over the years.  (There's a couple
> different versions hardwired in unwind.h for example).

In the last version of the patch (well, I know, it's 1/2 year now), I
removed the hard wired pt_regs value. You or Troy (didn't remember)
complained that this doesn't work *because* the definition changed
over years. And here we rely on the pt_regs structure of the dumping
kernel.

> So my biggest worry would be if this somehow breaks
> backwards-compatibility, but I'm presuming that you took
> that into account.  But anyway, I leave this all up
> to Troy.

Of course, that's possible. Always. But leaving existing bugs unfixed
is also not really a good idea. However, as I said, I'm willing to
split off the LKCD registers change (which is 90 %) and the dynamic
CPU calculation (which is 10 %) so that only the last remaining 10 %
can be included.

> Please build with "make warn" before submitting any patch
> and clean up the complaints.

Thanks for the hint. I'll do this in future!

> Also I'd prefer to not tinker with the netdump.c file.
> There is no /usr/include/stddef.h in the RHEL and FC8
> environments, and the /usr/include/linux/stddef.h has
> removed offsetof() in FC8 for some reason?  In any case,
> I'd prefer leaving it alone.

I cannot imagine this. "man offsetof" gives me

SYNOPSIS
       #include <stddef.h>

       size_t offsetof(type, member);

CONFORMING TO
       C89, C99, POSIX.1-2001.

So either the manpage is completely wrong, you're wrong or FC8 and
RHEL don't conform to the standards mentioned.

> Because of the builtin array sizes that I long ago
> painted crash into a corner with, I'd also prefer keeping
> NR_CPUS to its minimum.  I have no problem updating it if
> necessary later, so 4096 is preferable to overkilling
> it with 16384 at this time. 

Ok, then we update it to 4096. I have no objections. It wasn't even my
idea to update it to 16384.

> I don't see how that could be a problem?  If it is, you can always
> release the SUSE version with the larger value -- I'm sure that
> you're almost never in sync with the upstream version anyway, right?
> (I can't even do that with RHEL errata...)

No, I never sync to mainline for released SLES versions. However, I
always try to keep the number of custom patches of Factory (latest
openSUSE release) as small as possible because:

  o Less work on update. crash has frequent releases.

  o Easier to report bugs mainline. I even see that users/customers
    ask on that mailing list. That's difficult if the SUSE crash
    differs from the mainline crash too much.



Thanks,
   Bernhard