KGDB 2..26 fails to wait while booting

KGDB 2..26 fails to wait while booting

[amruth]

Hi
I have created 2.6.26 kernel with KGDB enabled but the system fails to wait. Can anybody provide me detailed info on how to setup the grub configuration to wait until gdb connects from development machine. 
Thanks
Amruth p.v


      

Re: KGDB 2..26 fails to wait while booting

[Jason Wessel]

amruth wrote:
> Hi
> I have created 2.6.26 kernel with KGDB enabled but the system fails to
wait. Can anybody provide me detailed info on how to setup the grub
configuration to wait until gdb connects from development machine.
> Thanks
> Amruth p.v
>
>
>      
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
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What parameters did you use in grub?

Generally speaking you have to setup the boot parameters to be something
like:

kgdboc=ttyS0,115200 kgdbwait

Jason.

KGDB 2..26 fails to wait while booting

[amruth]

Thanks Jason. I got it working, but is it possible to enable kdb with kgdb. 
How can I debug the kernel early. In kdb we have option called as kdb=early, can we do the same in kgdb. I tried to set breakpoint in kgdb at start_kernel, it looks like kgdb executed past the start_kernel code.Hence break point does not work.
Please let me know how to enable debug early kernel option in KGDB. 

Thanks
Amruth p.v


--- On Mon, 8/18/08, Jason Wessel <jason.wessel@windriver.com> wrote:

> From: Jason Wessel <jason.wessel@windriver.com>
> Subject: Re: KGDB 2..26 fails to wait while booting
> To: amruth_pv@yahoo.com
> Cc: linux-kernel@vger.kernel.org
> Date: Monday, August 18, 2008, 9:05 AM
> amruth wrote:
> > Hi
> > I have created 2.6.26 kernel with KGDB enabled but the
> system fails to
> wait. Can anybody provide me detailed info on how to setup
> the grub
> configuration to wait until gdb connects from development
> machine.
> > Thanks
> > Amruth p.v
> >
> >
> >      
> >
> > --
> > To unsubscribe from this list: send the line
> "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at 
> http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/
> 
> What parameters did you use in grub?
> 
> Generally speaking you have to setup the boot parameters to
> be something
> like:
> 
> kgdboc=ttyS0,115200 kgdbwait
> 
> Jason.
> 
> --
> To unsubscribe from this list: send the line
> "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at 
> http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/


      

Re: KGDB 2..26 fails to wait while booting

[Jason Wessel]

amruth wrote:
> Thanks Jason. I got it working, but is it possible to enable kdb with kgdb. 
> How can I debug the kernel early. In kdb we have option called as kdb=early, can we do the same in kgdb. I tried to set breakpoint in kgdb at start_kernel, it looks like kgdb executed past the start_kernel code.Hence break point does not work.
> Please let me know how to enable debug early kernel option in KGDB. 
>
>   

This is a limitation of the kgdb which in the mainline sources.  The
kgdb core itself can support early debugging.

The kgdboc I/O module does not support early debugging however because
it waits for the tty driver to get setup.  There is an 8250_kgdb kernel
module which supports debugging from an ealier point than the kgdboc
driver but this is not in the main line sources.  You can get it from
the kgdb branch.

IE:

http://git.kernel.org/?p=linux/kernel/git/jwessel/linux-2.6-kgdb.git;a=commitdiff_plain;h=2e92260276c0948e260bb8a8399e20dfb5713f70

and

http://git.kernel.org/?p=linux/kernel/git/jwessel/linux-2.6-kgdb.git;a=commitdiff_plain;h=03e9da089af8813ac1947e5a078906652bd2fbb7

Jason.