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Re: gdb/1933: When calling a function from gdb, unexpectedSIGTRAPs are received
- From: Peter Wainwright <prw at ceiriog1 dot demon dot co dot uk>
- To: nobody at sources dot redhat dot com
- Cc: gdb-prs at sources dot redhat dot com,
- Date: 3 May 2005 13:08:05 -0000
- Subject: Re: gdb/1933: When calling a function from gdb, unexpectedSIGTRAPs are received
- Reply-to: Peter Wainwright <prw at ceiriog1 dot demon dot co dot uk>
The following reply was made to PR gdb/1933; it has been noted by GNATS.
From: Peter Wainwright <prw@ceiriog1.demon.co.uk>
To: urs.hunkeler@epfl.ch
Cc: gdb-gnats@sources.redhat.com, nobody@sources.redhat.com,
gdb-prs@sources.redhat.com
Subject: Re: gdb/1933: When calling a function from gdb, unexpected
SIGTRAPs are received
Date: Mon, 02 May 2005 18:55:53 +0100
That's surprising, Urs. I am now working on a vanilla 2.6.11.5
(kernel.org) kernel and my problem has disappeared. I managed
to get a test case debugging a very simple "Hello World"
type application, and managed to replicate the problem consistently.
The problem was the second consecutive invocation of a function
after a single step. After the single step, "print $eflags"
showed that the trap flag (0x100) was still set. For some reason
this did not affect the first invocation of the function
(you call this a "call dummy"?), however, the second would
always break after every instruction, as you would expect since
the trap flag was not cleared properly. I suspect the kernel
implementation of ptrace (arch/i386/ptrace.c) or something similar.
--
Peter Wainwright <prw@ceiriog1.demon.co.uk>