Re: remote gdb, kgdb and ddb

On Tuesday 31 October 2006 20:13, Julian Elischer wrote:
> it's been a bew years since I did this..
> 
> some questions..
> 
> why kgdb instead of gdb -k ?
> 
> for remote, gdb seems to work fine
> kgdb -r /dev/cuad0 kernel.debug   thinks it's working but seems to get 
> confused a lot..

No idea, ask marcel perhaps.  I only use kgdb on coredumps.

> gdb with the following .gdbinit file seems to work as well.
>   file kernel.debug
>   set verbose 1
>   set remotebreak 1
>   set remotebaud 9600
>   set remotedevice /dev/cuad0
>   target remote /dev/cuad0
> 
> though I'm not convinced I'm seeing the last frame in which the
> trap occurs. (ddb shows one  more frame).

This is one of the things kgdb fixes (it has frame sniffers for trapframes).
 
> Now that I have my machine in remote gdb, the documentation
> (as sparse as it is) doesnt't say how to make the machine reboot.
> 
> from ddb I can do 'call cpu_reset' which seems to work, but
> I haven't succedded in making gdb do anything similar,
> nor to drop back into ddb. At one stage 'detach' used to do that
> but it seems to have stopped working.

Try the following from src/tools/debugscripts/gdbinit.kernel:

# Switch back to ddb
define ddb
set boothowto=0x80000000
s
end
document ddb
Switch back to ddb.
end

I think I used to use that a few years ago.

-- 
John Baldwin