[Crash-utility] Re: source line numbers and modules (on x86_64)

[Mike Snitzer]

On Wed, Apr 30, 2008 at 6:43 PM, Dave Anderson <anderson at redhat.com> wrote:
>
> Mike Snitzer wrote:
>
> > Hi,
> >
> > I searched the archives and found that you've discussed an issue I'm
> > seeing with x86_64 kernels where crash doesn't have line numbers for
> > modules' symbols:
> > https://www.redhat.com/archives/crash-utility/2008-January/msg00021.html
> >
> > I'm using crash-4.0-6.3 on a RHEL5U1 x86_64 system with a custom
> > 2.6.22.19 kernel.  Given that the RHEL5U1 x86_64 kernels clearly do
> > provide accurate line numbers for modules, has anyone identified how
> > that is?  I have to believe the redhat kernel is patched to fix this
> > issue.
> >
> > I looked over the various redhat patches that are applied to RHEL5's
> > 2.6.18 sources but can't see a patch that stands out as specifically
> > addressing this x86_64 issue.  But I could easily be overlooking some
> > patch.
> >
> > please advise, thanks.
> > Mike
> >
> > ps. please cc me as I've not yet been able to join the list
> >
> >
>  You're on the list now...
>
>  Anyway, there are no kernel patches applied to RHEL5 kernels
>  to make it work that I'm aware of.  That being said, I don't
>  have an answer as to why they don't work for modules on your
>  custom kernel (or why they don't work in RHEL4 kernels...).

I configured my x86_64 kernel to be relocatable.  Could this be the
reason for modules' line number debug data being off?  From:
http://people.redhat.com/anderson/crash.changelog.html#4_0_4_5

"Using /proc/kallsyms or a --reloc=[size] as a command line argument
 is similar to using a System.map file, in that it results in the loss
 of the use of line number debug data."

Still doesn't explain why RHEL4 isn't happy in this regard either...

I'm trying a non-relocatable variant of my kernel now and will report
back with the results.

Mike