Missing a step in new(er) Remote gdb/kdb setup?

Lonnie VanZandt lonnie.vanzandt at ngc.com
Thu Aug 11 16:14:40 GMT 2005


	The protocol sync issue is now gone - but the host side kgdb core dumps 
immediately after reporting the current break point of the target:

lonnie at aperiodic$ kgdb -r /dev/cuaa0 /tmp/kernel.debug
[GDB will not be able to debug user-mode threads: /usr/lib/libthread_db.so: 
Undefined symbol "ps_pglobal_lookup"]
GNU gdb 6.1.1 [FreeBSD]
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This GDB was configured as "i386-marcel-freebsd".
(no debugging symbols found)...Switching to remote protocol
0xc0634d14 in kdb_enter ()
Segmentation fault (core dumped)

If I run gdb on the kgdb.core file, it shows a corrupted - or at least massive 
- stack frame with no symbolic information.

Is there a kgdb patch/update for 5.4 release p3 that I should apply? Or 
perhaps some permission/resource issue on the host that needs to be 

On Thursday 04 August 2005 06:10 pm, Marcel Moolenaar wrote:
> On Aug 4, 2005, at 9:27 AM, Lonnie VanZandt wrote:
> > Ok, so I infer that the startup sequence should be:
> >
> >     1. enter kdb on target
> >     2. type gdb on target
> >     3. type s on target
> >     4. start kgdb on host with -r option
> >     5. wait for good connection
> >     6. load symbol table files on host
> >     7. get on with the debugging
> >
> > Is this correct?
> Yes.
> > (There was not this requirement for strict ordering in the
> > prior version of the remote protocol - or else it was at least more
> > tolerant)
> I think the problem is that on the one hand the kernel sends a packet to
> inform GDB that it has stopped and on the other hand GDB sends various
> packets to figure out what the target is capable of. When this happens
> at the same time, GDB gets confused. There has not been a change in KDB
> and the GDB backend that makes this worse than before. It's all because
> of a new version of GDB.
> FYI,

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