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Re: Debugging using GDB and gdbserver

To: Justin Wojdacki <justin.wojdacki@analog.com>
Subject: Re: Debugging using GDB and gdbserver
From: Daniel Jacobowitz <dmj+@andrew.cmu.edu>
Date: Sat, 15 Jun 2002 15:38:31 -0500
Cc: linux-mips@oss.sgi.com
In-reply-to: <3D0BA3C4.79ED2B5D@analog.com>; from justin.wojdacki@analog.com on Sat, Jun 15, 2002 at 01:29:56PM -0700
References: <3D0B9D14.BFE27F7E@analog.com> <20020615151413.A19123@crack.them.org> <3D0BA3C4.79ED2B5D@analog.com>
Sender: owner-linux-mips@oss.sgi.com
User-agent: Mutt/1.2.5i
On Sat, Jun 15, 2002 at 01:29:56PM -0700, Justin Wojdacki wrote:
> Daniel Jacobowitz wrote:
> > 
> > On Sat, Jun 15, 2002 at 01:01:24PM -0700, Justin Wojdacki wrote:
> > >
> > > How does GDB work under MIPS Linux? I'm trying to do a bring-up of an
> > > embedded device, and it looks like the kernel is missing the code
> > > needed to handle software breakpoints. Are there patches that need to
> > > be applied to the kernel?
> > 
> > No.  If you use a current GDB (I recommend 5.2 or CVS) it should work
> > just fine, if you are using a recent kernel (you didn't mention what
> > version you were looking at).
> > 
> > --
> > Daniel Jacobowitz                           Debian GNU/Linux Developer
> > MontaVista Software                         Carnegie Mellon University
> 
> Sorry, I'm using the 2.4.10 kernel and GDB 5.2. What I see happening
> is the BREAK 5 instruction from a software breakpoint is hit, and the
> kernel loops continuously on that, as it appears to have no way to
> deal with that exception. I'm running gdbserver on the MIPS target and
> gdb as a cross-debugger on an x86 host (RedHat 7.1). To me, it looks
> like when the debugging breakpoint is hit, gdbserver should get
> scheduled to run and handle the breakpoint, but instead the child
> keep's getting scheduled. 

Software breakpoints have worked at least as far back as 2.4.2.  This
most likely means that the exception handling for your board is broken.

-- 
Daniel Jacobowitz                           Debian GNU/Linux Developer
MontaVista Software                         Carnegie Mellon University

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