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Date: Sun, 07 Nov 2004 02:38:00 -0000
From: Daniel Jacobowitz <drow@false.org>
To: Andrew de Quincey <adq_dvb@lidskialf.net>
Cc: gdb@sources.redhat.com
Subject: Re: GDB 6.2.1 with powerpc platform and uclibc and user breakpoint problem
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On Sat, Nov 06, 2004 at 02:34:45PM +0000, Andrew de Quincey wrote:
> -- this is the internal breakpoint on _dl_debug_state being triggered. I see this in my kernel
> tracing in the trap handlers.
> 
> RX: m10000548,4
> TX: 7d821008
> RX: M10000548,4:38000000
> TX: OK
> RX: m300018d4,4
> TX: 7d821008
> RX: M300018d4,4:801c005c
> TX: OK
> 
> -- GDB is clearing the breakpoints *INCLUDING MY USER BREAKPOINT* - it has removed the
> trap instruction and set it back to 0x38000000. why is it doing this!?!

So that it can step past the breakpoint.

> RX: m10010904,b0
> TX: 00000001000000010000000c1000036c0000000d1000089c000000041000012800000005100002680000000610000
> RX: m30005004,4
> TX: 00000000
> RX: vCont;s

That's a step request.

> TX: T0b01:7ffffa60;40:1000056c;

That's a segfault.  Your kernel has failed to implement
PTRACE_SINGLESTEP correctly.  This is a common problem on older 4xx
kernels.

-- 
Daniel Jacobowitz