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

[Pedro Alves <palves@redhat.com>]

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 libthread_db.so to insert breakpoints at magic
> locations in libpthread.so, in order to break at thread creation and
> thread death.
>
> Support for thread events was removed from GDBServer as patch:
> https://sourceware.org/ml/gdb-patches/2015-11/msg00466.html
>
> This patch removes support for thread events in GDB.
>
> No regressions found on Ubuntu 14.04 x86_64.
>
> gdb/ChangeLog:
> 	* 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))



> -  /* 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?



> @@ -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.

Thanks,
Pedro Alves