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

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

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.

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.


H.J.
---
2001-11-14  H.J. Lu  (hjl@gnu.org)

	* mips-tdep.c (heuristic_proc_desc): Read register only when
	target is running.

--- gdb/mips-tdep.c.break	Mon Aug  6 17:13:24 2001
+++ gdb/mips-tdep.c	Wed Nov 14 13:28:17 2001
@@ -1860,7 +1860,12 @@ static mips_extra_func_info_t
 heuristic_proc_desc (CORE_ADDR start_pc, CORE_ADDR limit_pc,
 		     struct frame_info *next_frame)
 {
-  CORE_ADDR sp = read_next_frame_reg (next_frame, SP_REGNUM);
+  CORE_ADDR sp;
+  
+  if (target_has_execution)
+    sp = read_next_frame_reg (next_frame, SP_REGNUM);
+  else
+    sp = 0;
 
   if (start_pc == 0)
     return NULL;