[Crash-utility] mod -S and debuginfo kernel rpm

[Dave Anderson]

----- "Michael Holzheu" <holzheu at linux.vnet.ibm.com> wrote:

> > So there would be that restriction as to the *relative* locations of
> > the .ko and .ko.debug files.  But I don't think that's really all that
> > burdensome.  
> > 
> > Comments?
> 
> I think that's a good proposal!
> 
> Michael

OK, so here's the proposal:

- Make the currently-existing "mod -S <release-dir>" command find both the
  stripped "<module>.ko" and its associated "<module.ko.debug>"

Prerequisite:

- Both the "<module>.ko" and "<module.ko.debug>" files must be located in
  or under the <release-dir>.

The search mechanism for the stripped "<module>.ko" file would be:

- Search the complete <release-dir> tree for "<module>.ko".
. When found, save the relative directory pathname containing the file,
  where the <relative-dir-path> would be rooted from <release-dir>. 

The search mechanism for the associated "<module>.ko.debug" file would be
done in this order: 

  1. Search the <release-dir>/<relative-dir-path> directory
  2. Search the <release-dir>/<relative-dir-path>/.debug directory
  3. Search the <release-dir>/usr/lib/debug/<relative-dir-path> directory

This scheme would allow an alternate module/module-debuginfo setup to
be done like so:

  $ mkdir <release-dir>
  $ cd <release-dir>
  $ rpm2cpio kernel-<release>.rpm | cpio -idv
  $ rpm2cpio kernel-debuginfo-<release>.rpm | cpio -idv

And then the modules and their debuginfo data could be loaded using
the current alternative mechanism:

  crash> mod -S <release-dir>

Also, because of the 1-2-3 debuginfo search order above, this would allow
the copying of "<module>.ko" and "<module>.ko.debug" files into the same
directory anywhere underneath <target-dir>, or in the ".debug" subdirectory
of the directory containing "<module>.ko".

That being the case, it would be easy to handle per-release oddities such
as the RHEL /lib/modules/<release>/updates directory, by simply copying the
associated <module>.ko.debug file into the same directory as its stripped file. 

Guy -- are you on board with this?

Dave