Re: PATCH: Re: [RFHelp] Linux, threads, and regsets in thread_db

["H . J . Lu" <hjl@lucon.org>]

On Thu, Nov 15, 2001 at 11:48:41AM -0500, Daniel Jacobowitz wrote:
> On Wed, Nov 14, 2001 at 01:45:21PM -0800, H . J . Lu wrote:
> > On Wed, Oct 03, 2001 at 09:10:07PM -0400, Daniel Jacobowitz wrote:
> > > > > 
> > > > 
> > > > How far have you gone on Linux/mips? I know gdb 5.1 doesn't work with
> > > > threads on Linux/mips. Does your change fix it? I'd like to clean up
> > > > glibc for mips on this.
> > > 
> > > Yes.  Debugging threads works reasonably well.  I'm going to do more
> > > work about this in the next couple of months too, I think; after I go
> > > back to gdbserver for a little while.
> > 
> > I am still having problems with threads on mips. I cannot set break
> > point after target has run:
> > 
> > (gdb) run
> > ...
> > (gdb) b main
> > reading register sp (#29): No such process.
> > 
> > The problem is gdb tries to read sp register in thread mode. This patch
> > seems to work for me.
> 
> This should not be a problem.  It works fine for me.  I'll step through
> it later tonight and try to figure out what the difference is from what
> you're seeing.

In my case, gdb in thread mode will cal "fetch_register" in infptrace.c.
Since nothing is running, I got

reading register sp (#29): No such process.

I don't know why it works for you.

> 
> > Another problem is when I set a break point in a thread function, only
> > the first thread stops. I got
> > 
> > (gdb) b process
> > Breakpoint 1 at 0x400a38: file Examples/ex1.c, line 14.
> > (gdb) r
> > Starting program: /export/build/gnu/glibc/build-mipsel-linux/linuxthreads/ex1 
> > [New Thread 1024 (LWP 26552)]
> > [New Thread 2049 (LWP 26569)]
> > [New Thread 1026 (LWP 26570)]
> > [Switching to Thread 1026 (LWP 26570)]
> > 
> > Breakpoint 1, process (arg=0x1000) at Examples/ex1.c:14
> > 14        fprintf (stderr, "Starting process %s\n", (char *) arg);
> > ...
> > Program received signal SIGTRAP, Trace/breakpoint trap.
> > [Switching to Thread 1024 (LWP 26552)]
> > 0x2ab8de24 in __syscall_rt_sigsuspend () at soinit.c:56
> > 56      soinit.c: No such file or directory.
> > 
> > But it may be a kernel bug.
> 
> Something is suspicious here.  The process in sigsuspend should have
> been stopped with SIGSTOP, not SIGTRAP...  is this an example program
> from glibc?

Yes, linuxthreads/ex1 from glibc.

> 
> > H.J.
> > ---
> > 2001-11-14  H.J. Lu  (hjl@gnu.org)
> > 
> > 	* mips-tdep.c (heuristic_proc_desc): Read register only when
> > 	target is running.
> 
> I can't see why this changes behavior in the way you're seeing.  I'm

Why do you think that? Why does anyone want to read a register when
nothing is running?

> pretty sure it isn't right.



H.J.