Re: PR13901

[Tristan Gingold <gingold at adacore dot com>]

On Apr 2, 2012, at 4:16 PM, Pedro Alves wrote:

> On 04/02/2012 03:06 PM, Tristan Gingold wrote:
> 
>> 
>> On Apr 2, 2012, at 3:56 PM, Pedro Alves wrote:
> 
> 
>>> Why does GDB need to touch the shell's registers at all in the first place?
>> 
>> I haven't checked why.
> 
> 
> Well, I claim that it shouldn't.  :-)  The whole existence of
> fork-child.c:startup_inferior was justified on making GDB not touch the
> shell.  We used to have the startup phase go through the whole
> wait_for_inferior shebang, which was problematic as it touched the shell.
> 
>> 
>>> If we can't skip darwin_set_sstep for all continues that are not single-steps,
>>> we could at least skip those while starting up (when continuing the shell
>>> until we see enough execs).  That'd suggest a new flag like
>>> darwin-nat.h:struct private_inferior->starting_up, set and cleared in
>>> darwin_create_inferior, and then making darwin_resume_thread do:
>>> 
>>> -     /* Set single step.  */
>>> -     inferior_debug (4, _("darwin_set_sstep (thread=%x, enable=%d)\n"),
>>> -                     thread->gdb_port, step);
>>> -     darwin_set_sstep (thread->gdb_port, step);
>>> +     /* Avoid touching the $SHELL process, and go straight to resuming it.  */
>>> +     gdb_assert (!inf->private->starting_up || !step);
>>> +     if (!inf->private->starting_up)
>>> +        {
>>> +         /* Set single step.  */
>>> +         inferior_debug (4, _("darwin_set_sstep (thread=%x, enable=%d)\n"),
>>> +                         thread->gdb_port, step);
>>> +         darwin_set_sstep (thread->gdb_port, step);
>>> 
>>> WDYT?
>> 
>> Yes, it might be cleaner.
>> 
>> Honestly, I'd prefer to get rid of the shell step and directly execute the user program - or at least have an option to do that.  I think I also understand the cons of this approach.
> 
> 
> I'd be glad to see STARTUP_WITH_SHELL turned into a run-time option.

Good to know that.

>  I think there's
> a PR open for that even.  However, we need the shell at least for argument globbing,
> as in, e.g., debugging `ls *', so I don't think we could make it off by default,
> which practically renders it an orthogonal feature.

Sure.

Tristan.