System GDB 7.3 upgrade: Stuck on quirk with kgdb

John Marino dragonflybsd at
Sun Apr 10 10:58:44 PDT 2011

The GDB project is going to release GDB 7.3 in a few days.  I thought 
this would be a good time to upgrade the debugger.  Using their CVS from 
the recently created 7.3 branch, I was able to successfully build gdb 
and kgdb within the /usr/src infrastructure.  The patches to upgrade the 
system debugger to 7.3 are here:   (1.8M)

Regular gdb seems to work fine.  The problem is with kgdb.  The first 
issue that that typing "kgdb" at the prompt will show that the kernel 
module symbols aren't getting read in.  By commenting out line 138 from 
gnu/usr.bin/gdb/kgdb/trgt.c and building again, the kernel modules will 
get read in as expected.

That line is: 

It was added 2009/12/28 here:
The second problem is the last line of output before you get the prompt 
on kdgb is "No registers.".  Asking for a backtrace results in a display 
of "No stack.".

Both problems happen on both platforms.  I don't have a clue about why 
the "default_child_has_registers" function from target.c is coming back 
as false (well, yes, because the inferior ptid structure is all zeros 
but I don't know why).

Anyway, I probably exhausted my skill just porting gdb and getting kgdb 
to build.  I would be grateful for help fixing and testing kgdb so that 
we might bring it into base post-release 2.10.  By the way, if you build 
 k/gdb with debug flags, you can use the newly-built gdb to debug the 
newly-built kgdb.


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