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

[Michael Holzheu]

Am Dienstag, den 21.04.2009, 17:34 +0200 schrieb Michael Holzheu:
> Am Dienstag, den 21.04.2009, 11:17 -0400 schrieb Dave Anderson:
> > Hi Michael,
> > 
> > I knew this sounded familiar, but there is an option for adding
> > an alternative search directory starting point to "mod -S":
> > 
> >   crash> help mod
> > 
> >   NAME
> >     mod - module information and loading of symbols and debugging data
> > 
> >   SYNOPSIS
> >     mod [ -s module [objfile] | -d module | -S [directory] | -D | -r | -o ]
> > 
> >   ... [ snip ] ...
> > 
> >          -S [directory]  Load symbolic and debugging data from the object file
> >                          for all loaded modules.  For each module, a search
> >                          will be made for an object file consisting of the
> >                          module name with a .o or.ko suffix, starting at the
> >                          /lib/modules/<release> directory of the host system.
> >                          If a directory argument is appended, then the search
> >                          will be restricted to that directory.
> >   ... [ snip ] ...
> > 
> > However -- although this option would allow you to specify your local
> > directory tree containing the stripped module files, I don't think that
> > the gdb algorithm will be able to find the associated .ko.debug files
> > (unless you moved them into the same directory).
> > 
> > As I recall, the [directory] option above was put in place back in the day
> > when the modules were not split into .ko and .ko.debug files.  I may be
> > wrong, but I don't think so.  Give it a shot anyway.
> 
> That's what I used. In particular I did the following:
> 
> # mkdir mydump
> # cd mydump
> # rpm2cpio kernel-2.6.18-128.el5.s390x.rpm | cpio -idv
> # rpm2cpio kernel-debuginfo-2.6.18-128.el5.s390x.rpm | cpio -idv
> 
> Then I called:
> 
> # mod -S lib/modules/2.6.18-128.el5/
> 
> That only loads the stripped modules. It does not search locally.

... and as you already said. If we copy the .debug files into the lib
directory, it seems to work:

# mkdir mydump
# cd mydump
# rpm2cpio kernel-2.6.18-128.el5.s390x.rpm | cpio -idv
# rpm2cpio kernel-debuginfo-2.6.18-128.el5.s390x.rpm | cpio -idv
# cp -r usr/lib/debug/lib/modules/2.6.18-128.el5/*
lib/modules/2.6.18-128.el5/
# crash vmlinux dump

crah> mod -S lib/modules/2.6.18-128.el5/
crash> ptype struct eckd_count
type = struct eckd_count {
    __u16 cyl;
    __u16 head;
    __u8 record;
    __u8 kl;
    __u16 dl;
}

Maybe that is already sufficient.

Michael