Re: Remote Debugging on IXDP425

Daniel Jacobowitz
2003-12-03T21:29:17Z

On Wed, Dec 03, 2003 at 11:17:18AM -0800, Stephen A. Witt wrote:
> Thanks very much for the response, very dumb mistake on my part. I had
> built a gdb with an arm-linux target, but I inadvertantly used the normal
> i386 gdb when I first tried this. Using the arm-linux gdb that I had
> built, with the information you provided, I found that the breakpoint
> instruction being sent was 0x01009fef. The correct bp inst for an IXP425
> (a big-endian CPU) is 0xef9f0001. So I modified the breakpoint instruction
> value in gdb to 0xef9f0001 and breakpoints work now.

This is a GDB bug fixed in more recent versions of GDB.

> There are some other problems, like when I do 'step' or 'next' I get a
> "ptrace: bogus breakpoint trap". Floating point variable display doesn't
> work. So I'm looking into these.

The former is a Linux kernel bug. I sent Russell an explanation of the
problem and got no response. Just turn off the message.

> I just hacked in the changed breakpoint instruction value but it seems the
> correct way to do it would be to tell gdb during configuration that the
> target is an xscale CPU, and conditionally compile in the correct value.
> At first I thought I hadn't built gdb properly, but it doesn't appear that
> gdb-6.0 really supports an IXP425. Is this true?

ARM/Linux in big endian mode is definitely still a black sheep. None
of the GNU tools really support it out of the box, only various
vendors' tools.

--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer