[Dwarf-discuss] Application of DWARF to kernel analysis

[jeff nelson]

The linker on OpenVMS has this capability. When used with the /DSF
switch, the linker writes the debugger symbol table into a separate
file. The file has the same format as an executable program, but it
contains just debugging information. At the beginning of a debugging
session, the debugger first checks for the existence of a .DSF file.

-Jeff

On Mon, 2005-11-14 at 19:32 -0800, Chris Quenelle wrote:
> Hi Dave,
> 
> This is exciting.  At Sun, the kernel group has invented their own
> C-structure-describing debug format (called CTF) and they
> go through the same process of merging CTF type information.
> I've been trying to find time to implement something like
> that for dwarf, and now it seems that someone else has the same
> desire.
> 
> It looks like it's based on applying a bunch of patch diffs
> to a specific version of the libdwarf source tar file.
> Isn't that going to be an ongoing maintenance issue
> for them?
> 
> --chris
> 
> 
> 
> David Anderson wrote:
> > There is a new application of DWARF2 and I thought folks
> > on this list would be interested in hearing about it.
> > It recently moved to SourceForge where all can use it.
> > 
> > Cliff Wickman provided this summary at my request.
> > 
> > David Anderson,  davea at sgi dot com
> > 
> > -------------
> >                         Converting DWARF to DWARF
> > 
> >   Debugging the Linux kernel presents a need for thousands of kernel
> >   structure definitions.  But it is not possible to compile all the kernel
> >   include files at once.  So how do you collect all kernel structures?
> > 
> >   Someone in an SGI class once asked then-instructor Cliff Wickman 
> >   why we cannot compile the kernel and its modules with -g and then
> >   collect all their DWARF information into one file.  The answer was
> >   that we have no such tool.
> >   Hence the idea for dwarfextract.
> > 
> >   The program uses the DWARF consuming library routines to extract the
> >   types. It eliminates duplicates.  Then turns around and feeds them to
> >   the DWARF producing routines.  It creates a "kerntypes" file that looks
> >   like an ELF binary but contains nothing but DWARF information.
> > 
> >   This kerntypes file is used by the lcrash kernel debugger to
> >   cast memory images as any kernel type.
> > 
> >   The dwarfextract tool is part of the Linux Kernel Crash Dump (LKCD)
> >   project.  The project can be downloaded from sourceforge by:
> >     export CVSROOT=":pserver:anonymous at cvs.sourceforge.net:/cvsroot/lkcd"
> >     cvs login    # Press enter (eg no password) when prompted
> >     cvs -z3 co lkcd/7.X.X/lkcdutils
> >     cd lkcd/7.X.X/lkcdutils ; ./configure
> > -------------
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