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Re: [PATCH] Remove support for thread events without PTRACE_EVENT_CLONE in GDB.

On 12/10/2015 09:47 AM, Pedro Alves wrote:
On 12/09/2015 05:39 PM, Antoine Tremblay wrote:
Before, on systems that did not support PTRACE_EVENT_CLONE, both GDB and
GDBServer coordinated with to insert breakpoints at magic
locations in, in order to break at thread creation and
thread death.

Support for thread events was removed from GDBServer as patch:

This patch removes support for thread events in GDB.

No regressions found on Ubuntu 14.04 x86_64.

	* breakpoint.c (create_thread_event_breakpoint): Remove.
	(remove_thread_event_breakpoints): Remove.

That's still used:

  $ grep create_thread_event_breakpoint gdb/*
  gdb/aix-thread.c:  if (!create_thread_event_breakpoint (target_gdbarch (), pd_brk_addr))

Ouch, I had missed that one. I'll re-add the function.

Also I noticed I forgot to remove the declaration in breakpoint.h I'll fix that for remove_thread_event_breakpoint.

-  /* Under GNU/Linux, we have to attach to each and every thread.  */
-  if (target_has_execution
-      && tp == NULL)
-    {
-      int res;
-      res = lin_lwp_attach_lwp (ptid_build (ptid_get_pid (ptid),
-					    ti_p->ti_lid, 0));
-      if (res < 0)
-	{
-	  /* Error, stop iterating.  */

Is lin_lwp_attach_lwp used anywhere after this?

No indeed, Removing.

@@ -1592,24 +1200,10 @@ find_new_threads_callback (const td_thrhandle_t *th_p, void *data)

    if (ti.ti_tid == 0)
-      /* A thread ID of zero means that this is the main thread, but
-	 glibc has not yet initialized thread-local storage and the
-	 pthread library.  We do not know what the thread's TID will
-	 be yet.  Just enable event reporting and otherwise ignore
-	 it.  */

You shouldn't remove the whole comment -- it's still all correct
except the last sentence.

Yes I hesitated on that one, it felt like the reason for the comment was the last sentence so I removed it.

But I'm OK with leaving it there.

V2 follows in next mail.


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