cvs commit: src/gnu/usr.bin/gdb/kgdb kgdb.h kld.c trgt.c

John Baldwin jhb at
Wed Jan 30 06:22:56 PST 2008

On Wednesday 30 January 2008 04:47:06 am Doug Rabson wrote:
> On 29 Jan 2008, at 23:44, John Baldwin wrote:
> > jhb         2008-01-29 23:44:34 UTC
> >
> >  FreeBSD src repository
> >
> >  Modified files:
> >    gnu/usr.bin/gdb/kgdb kgdb.h kld.c trgt.c
> >  Log:
> >  - Rework the kld support to hook into GDB's shared library support.
> >    kgdb(8) now treats kld's as shared libraries relative to the kernel
> >    "binary".  Thus, you can use 'info sharedlibrary' to list the kld's
> >    along with 'sharedlibrary' and 'nosharedlibrary' to manage symbol
> >    loading and unloading.  Note that there isn't an easy way to  
> > force GDB
> >    to use a specific path for a shared library.  However, you can use
> >    'nosharedlibrary' to unload all the klds and then use  
> > 'sharedlibrary'
> >    to load specific klds where it gets the kld correct and use
> >    'add-kld' for the kld's where the default open behavior doesn't  
> > work.
> >    klds opened via 'sharedlibrary' (and during startup) do have their
> >    sections listed in 'info files'.
> >  - Change the 'add-kld' command to use filename completion to  
> > complete its
> >    argument.
> This was how it used to work long ago (I forget exactly how long). I  
> had things set up so that GDB's standard ELF shared library code would  
> find KLDs automatically - you can see remnants of this in link_elf.c  
> in 'ifdef GDB' sections which build an RTLD-like list of loaded files  
> which GDB looked for starting at the global symbol r_debug.

This might still work for remote kgdb as the current stuff in kgdb doesn't
handle remote kgdb.  The above works by redefining the so_ops to work such
that they traverse the linker_file list.  The GDB stuff in link_elf.c should
make it so that the solib-svr4 stuff works with klds.  I usually don't
include 'options GDB' in my kernels so didn't see that. :-/

I'll do some further testing to see if that still works.  I believe that live
kgdb on amd64 has some issues in general (I think the kernel side has bugs),
but I mostly use kgdb on crash dumps so don't run into that.

John Baldwin

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