Re: KGDB 2.0.3 with fixes and development in ethernet interface

[George Anzinger]

Amit S. Kale wrote:
> On Saturday 17 Jan 2004 6:53 am, George Anzinger wrote:
>
> > Pavel Machek wrote:
> >
> > > Hi!
> > >
> > >
> > > > KGDB 2.0.3 is available at
> > > > http://kgdb.sourceforge.net/kgdb-2/linux-2.6.1-kgdb-2.0.3.tar.bz2
> > > >
> > > > Ethernet interface still doesn't work. It responds to gdb for a couple of
> > > > packets and then panics. gdb log for ethernet interface is pasted below.
> > > >
> > > > It panics and enter kgdb_handle_exception recursively and silently. To
> > > > see the panic on screen make kgdb_handle_exception return immediately if
> > > > kgdb_connected is non-zero.
> > > >
> > > > Panic trace is pasted below. It panics in skb_release_data. Looks like
> > > > skb handling will have to changed to be have kgdb specific buffers.
> > >
> > > This seems to be needed (if I unselect CONFIG_KGDB_THREAD, I get
> > > compile error on x86-64).
> >
> > Amit, could you explain why this is an option?  It seems very useful and
> > not really too much code...
>
>
> It saves all registers before switch_to. It does that two times at present. 
> Once (implicit) register save by gcc and an explicit register save in 
> arch/<proc>/kernel/entry.S Second register save in kern_schedule generates a 
> pt_regs structure which gdb can get all registers at once from. If it's 
> omited, gdb has to figure out where gcc has saved registers from the 
> non-standards code in switch_to, which it can't do correctly all the time.
>
> We can have a check for (a new variable) debugger_enabled before calling 
> kern_schedule. That'll be add negligible overhead and will allow extra thread 
> info to be saved only when a debugger is enabled. There will not be any need 
> for CONFIG_KGDB_THREAD also.

I don't seem to have such a problem with the mm kgdb.  No kern_schedule there...

--
George Anzinger   george@xxxxxxxxxx
High-res-timers:  http://sourceforge.net/projects/high-res-timers/
Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml

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