Re: Does gdb 5.2 work with statically linked thread application under Linux?

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

On Thu, Mar 07, 2002 at 05:02:07PM -0500, Daniel Jacobowitz wrote:
> On Thu, Mar 07, 2002 at 01:39:28PM -0800, H . J . Lu wrote:
> > On Thu, Mar 07, 2002 at 02:48:41AM -0500, Daniel Jacobowitz wrote:
> > > On Wed, Mar 06, 2002 at 11:30:50PM -0800, H . J . Lu wrote:
> > > > Does gdb 5.2 work with statically linked thread application under
> > > > Linux? It doesn't work for me at all. It doesn't know any thread.
> > > > I have a patch which works for gdb 5.1. Now it doesn't work for 5.2
> > > > anymore.
> > > 
> > > My fault, I think.
> > > 
> > > The problem is that in a dynamically linked binary
> > > thread_db_new_objfile will be called for every library is loaded.  At
> > > this point current_target is "child", so target_has_execution is true.
> > > But with a static binary, the first time the function is called objfile
> > > is NULL, and the second time current_target is "exec" (which has
> > > target_has_execution set false).
> > > 
> > > Perhaps target_has_execution was not the right check after all, if
> > > "exec" has it set false (which makes fairly little sense to me...) or
> > > perhaps we need to call the hook again later.  Michael, any idea?
> > > 
> > 
> > What is the problem if "|| !target_has_execution" is removed? I removed
> > it. Gdb now works on statically linked thread application as well as
> > core file. Did I miss soemthing?
> 
> Try running 'info threads' on the corefile of a multithreaded
> application.  Recent Linux kernels will allow them to dump core.
> 
> I've also got a patch to put multiple threads into the corefile. 
> There's a sample corefile at:
>   http://crack.them.org/~drow/mtc2.tar.gz
> 
> 
> Without !target_has_execution, we try to use lin-lwp on the coredump. 
> That works very badly.
> 

This patch works for me.


H.J.
----
2002-03-07  H.J. Lu  (hjl@gnu.org)

	* target.h (target_corefile_hook): New prototype.

	* target.c (target_corefile_hook): New.

	* corelow.c (core_open): Call target_corefile_hook if needed.

	* thread-db.c (thread_db_corefile): New.
	(thread_db_new_objfile): Don't check target_has_execution.
	(_initialize_thread_db): Set target_corefile_hook to
	thread_db_corefile.

--- gdb/corelow.c.static	Wed Mar  6 22:30:49 2002
+++ gdb/corelow.c	Thu Mar  7 15:01:41 2002
@@ -303,6 +303,9 @@ core_open (char *filename, int from_tty)
 	     filename, bfd_errmsg (bfd_get_error ()));
     }
 
+  if (target_corefile_hook)
+    target_corefile_hook ();
+
   /* Looks semi-reasonable.  Toss the old core file and work on the new.  */
 
   discard_cleanups (old_chain);	/* Don't free filename any more */
--- gdb/target.c.static	Wed Mar  6 22:31:31 2002
+++ gdb/target.c	Thu Mar  7 14:54:50 2002
@@ -38,6 +38,8 @@
 
 extern int errno;
 
+void (*target_corefile_hook) (void);
+
 static void target_info (char *, int);
 
 static void cleanup_target (struct target_ops *);
--- gdb/target.h.static	Wed Mar  6 22:31:31 2002
+++ gdb/target.h	Thu Mar  7 14:54:38 2002
@@ -985,6 +985,8 @@ extern char *normal_pid_to_str (ptid_t p
 
 extern void (*target_new_objfile_hook) (struct objfile *);
 
+extern void (*target_corefile_hook) (void);
+
 #ifndef target_pid_or_tid_to_str
 #define target_pid_or_tid_to_str(ID) \
      target_pid_to_str (ID)
--- gdb/thread-db.c.static	Wed Mar  6 22:31:31 2002
+++ gdb/thread-db.c	Thu Mar  7 14:59:09 2002
@@ -479,13 +479,25 @@ disable_thread_signals (void)
 }
 
 static void
+thread_db_corefile (void)
+{
+  if (using_thread_db)
+    {
+      /* If the thread_db target is active, deactivate it now.  */
+      gdb_assert (proc_handle.pid == 0);
+      unpush_target (&thread_db_ops);
+      using_thread_db = 0;
+    }
+
+  keep_thread_db = 0;
+}
+
+static void
 thread_db_new_objfile (struct objfile *objfile)
 {
   td_err_e err;
 
-  /* Don't attempt to use thread_db on targets which can not run
-     (core files).  */
-  if (objfile == NULL || !target_has_execution)
+  if (objfile == NULL)
     {
       /* All symbols have been discarded.  If the thread_db target is
          active, deactivate it now.  */
@@ -1040,5 +1052,6 @@ _initialize_thread_db (void)
       /* Add ourselves to objfile event chain.  */
       target_new_objfile_chain = target_new_objfile_hook;
       target_new_objfile_hook = thread_db_new_objfile;
+      target_corefile_hook = thread_db_corefile;
     }
 }