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Re: gdb single step ?

To: Ian Soanes <ians@lineo.com>
Subject: Re: gdb single step ?
From: Fabrice Bellard <bellard@email.enst.fr>
Date: Tue, 24 Apr 2001 15:49:19 +0200 (MEST)
Cc: linux-mips@oss.sgi.com, rivers@lexmark.com
In-reply-to: <3AE57586.13A6968F@lineo.com>
Sender: owner-linux-mips@oss.sgi.com
Hi!

I was speaking about gdb support in user mode, not the gdb stub in the
kernel. Does someone use gdb to debug user space programs on linux-mips ?
Maybe someone added the PTRACE_SINGLESTEP command of the ptrace syscall in
recent mips kernel, but I do not have it in my kernel (linux-2.4.0 on sgi
site).

I patched gdb 5.0 so that single step on mips is correctly supported in
user mode. I also modified gdbserver so that it works when you debug mips
code in user mode.

Fabrice.

On Tue, 24 Apr 2001, Ian Soanes wrote:

> Ian Soanes wrote:
> > 
> > Ralf Baechle wrote:
> > >
> > > On Mon, Apr 23, 2001 at 06:31:20PM +0200, Fabrice Bellard wrote:
> > >
> > > > Did someone make a patch so that gdb can do single step on mips-linux ? 
> > > > If
> > > > not, do you prefer a patch to gdb or a patch in the kernel to support 
> > > > the
> > > > PTRACE_SINGLESTEP command ?
> > >
> > > Last I used GDB single stepping has been working fine for me, so I wonder
> > > what is broken?
> > >
> 
> <snip>
> 
> > 
> > 2/ Previously I've had some luck single stepping kernel and module code
> > with the kernel gdbstub (arch/mips/kernel/gdb-stub.c), so I ported the
> > relevant single stepping code into gdbserver. The results were much
> > better. The only thing that seems to be wrong now is stepping over
> > function calls isn't working quite right. I can step into functions OK
> > though.
> > 
> 
> <snip>
> 
> Hi,
> 
> Sorry, I made a mistake (forgetting to clear a breakpoint) when I ported
> the stub single step code into gdbserver. As far as I can tell, single
> stepping works fine now.
> 
> BTW, should I be worried about MIPS16 instructions? (single step
> breakpoints are always placed on a 4 byte increment) ...or is that a
> silly question?
> 
> Best regards,
> Ian
> 


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