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Re: Itanium and GDB on 2.6.x kernels with pthreads
On Wed, Sep 07, 2005 at 05:23:56PM +0100, David Lecomber wrote:
> Dear all,
>
> Attached is a simple program, and simple script for GDB (current CVS,
> and previous versions)
>
> gcc -o pf -g pf.c -lm -lpthread
>
> gdb ./pf < gdb.script
>
> The script is a break main and then 'next' four times, followed by quit.
>
> On a 2.4.21 Itanium system, it's quick and quits happily.
>
> On a 2.6.5 Itanium, it hangs during the later nexts. Does anyone have a
> more recent Itanium they could try and see if this is a transient kernel
> issue?
And on 2.4.27 (-dsa-itanium-smp, on one of Debian's machines,
merulo.debian.org) it hangs during the first next. Thread debugging is
completely hosed. That's using the installed GDB 6.3.
Using a GDB I've built from CVS I get the same result.
If I strace gdb, it segfaults at the run command. It's not the same
problem you're seeing, because gdb is not consuming CPU.
CW: waitpid 17370 received Trace/breakpoint trap (stopped)
CW: waitpid 17370 received Trace/breakpoint trap (stopped)
CW: waitpid 17370 received Illegal instruction (stopped)
[Thread debugging using libthread_db enabled]
[New Thread 16384 (LWP 17370)]
LLR: PTRACE_SINGLESTEP process 17370, 0 (resume event thread)
LLW: waitpid 17370 received Trace/breakpoint trap (stopped)
LLW: Candidate event Trace/breakpoint trap (stopped) in LWP 17370.
LLTA: PTRACE_PEEKUSER LWP 17370, 0, 0 (OK)
SEL: Select single-step LWP 17370
LLW: trap_ptid is process 17370.
LLR: PTRACE_CONT process 17370, 0 (resume event thread)
LLW: waitpid 17370 received Illegal instruction (stopped)
LLW: Candidate event Illegal instruction (stopped) in LWP 17370.
LLTA: PTRACE_PEEKUSER LWP 17370, 0, 0 (OK)
LLR: PTRACE_SINGLESTEP process 17370, 0 (resume event thread)
Those sigill's should not be there, should they? Something is
seriously broken in ia64-land... I get them even running
single-threaded, but they're ignored because they happen at
breakpoints. But I'm not convinced that they don't indicate a real
problem somewhere.
And single-steps take me nowhere useful, and most local variables can't
be displayed.
Without knowing something useful about ia64, I don't think I can
usefully debug this, and there's no guarantee that it's even the same
problem you're seeing. Sorry.
--
Daniel Jacobowitz
CodeSourcery, LLC