From: Oleg Nesterov <oleg@redhat.com>
To: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Roland McGrath <roland@redhat.com>,
archer@sourceware.org, utrace-devel@redhat.com
Subject: Re: Q: %Stop && gdb crash
Date: Tue, 03 Aug 2010 15:09:00 -0000 [thread overview]
Message-ID: <20100803150656.GA8043@redhat.com> (raw)
In-Reply-To: <20100803133627.GB16669@host1.dyn.jankratochvil.net>
On 08/03, Jan Kratochvil wrote:
>
> On Tue, 03 Aug 2010 14:24:34 +0200, Oleg Nesterov wrote:
> > >
> > > So I assumed it is always safe to resend the notification unless gdb already
> > > sent vStopped. Since it is not clear to me when it makes sense to resend it,
> > > currently gdbstub does re-send every time /proc/ugdb reports the new event
> > > (T00 in this case). I agree this is not optimal, but this looks correct to me.
> >
> > I'll change gdbstub to never resend the notification to avoid the problem.
>
> Yes, I has been now just writing you such reply.
Sure, will do.
> > But probably gdb should be fixed anyway.
>
> There are so many serious bugs in GDB affecting regular GDB usage...
OK, so I assume that the current behaviour of gdbstub is correct, even
if stupid.
> > To avoid the unnecessary details, consider the oversimplified example,
> >
> > $ sleep 10000&
> > [1] 2923
> >
> > $ cat > SLEEP
> > set target-async on
> > set non-stop
> > target extended-remote :2000
> > file /bin/sleep
> > attach 2923
> > info registers
> > detach
> > ^D
> >
> > $ gdb <SLEEP
> > GNU gdb (GDB) 7.1
> > Copyright (C) 2010 Free Software Foundation, Inc.
> > License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> > This is free software: you are free to change and redistribute it.
> > There is NO WARRANTY, to the extent permitted by law. Type "show copying"
> > and "show warranty" for details.
> > This GDB was configured as "x86_64-unknown-linux-gnu".
> > For bug reporting instructions, please see:
> > <http://www.gnu.org/software/gdb/bugs/>.
> > (gdb) (gdb) (gdb) Remote debugging using :2000
> > (gdb) Reading symbols from /bin/sleep...(no debugging symbols found)...done.
> > (gdb) Attached to process 2923
> > [New Thread 2923.2923]
> > Target is executing.
> > (gdb) Detached from remote process 2923.
> > (gdb) quit
> >
> > And yes, gdb ignores %Stop and just detaches. But this is because
> > of another issue (which looks like a minor gdb bug to me), note the
> >
> > "Target is executing."
> >
> > above. This is the reply to "info registers". Why? OK, yes, it is
> > executing.
>
> Yes.
>
>
> > Then send vCont:t ? "attach PID" means attach and stop it, no?
>
> But it is not yet stopped that time.
Well. And how can I stop it?
Once again, this all works in CLI mode. And this looks very natural
(gdb) attach PID
(gdb) info registers
As a newbie user of gdb, I expected it is gdb who should take care
and stop the tracee after "attach". And please remember, "interrupt"
doesn't help.
OK, please ignore. Now that I know I can't trust 'gdb < BATCH' I do
not use this.
> > Can't resist, I spent a lot of time trying to understand what is wrong.
>
> Nothing, you should wait till GDB reports the inferior has stopped.
Yes, yes, now I understand this. Once again, I was greatly confused
because I didn't know that CLI mode makes the difference. Even if I
enter the commands via copy-and-paste, gdb always "completes" this
attach before it reacts to "info registers".
And there were other issues which I didn't understand when I tried
to solve this problem...
> It is
> easy/normal in the GDB testsuite
Hmm. How? probably the tests in testsuite wait for something which
looks like "[Thread 5683.5683] #1 stopped." from gdb?
> > I tried to achieve the same results with /proc/ugdb doing
> > "$ gdb < BATCH_FILE" with the same commands.
>
> Maybe you can write a new *.exp testcase for such testing.
I guess you want me to learn /usr/bin/expect ;)
Oleg.
next prev parent reply other threads:[~2010-08-03 15:09 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-16 20:54 Q: mutlithreaded tracees && clone/exit Oleg Nesterov
2010-07-16 21:40 ` Roland McGrath
2010-07-18 17:51 ` Oleg Nesterov
2010-07-18 18:04 ` Oleg Nesterov
2010-07-18 20:22 ` Roland McGrath
2010-07-19 13:44 ` BUG: add_thread_silent()->switch_to_thread(minus_one_ptid) is wrong Oleg Nesterov
2010-07-19 15:36 ` Oleg Nesterov
2010-07-19 16:01 ` Q: mutlithreaded tracees && clone/exit Jan Kratochvil
2010-07-19 22:57 ` Roland McGrath
2010-07-20 13:18 ` Oleg Nesterov
2010-07-20 14:04 ` BUG? gdb, non-stop && c -a Oleg Nesterov
2010-07-20 14:12 ` Jan Kratochvil
2010-07-20 14:49 ` Oleg Nesterov
2010-07-20 15:08 ` Jan Kratochvil
2010-07-20 15:28 ` Oleg Nesterov
2010-07-20 19:43 ` Roland McGrath
2010-07-21 7:59 ` Oleg Nesterov
2010-07-21 8:10 ` Jan Kratochvil
2010-07-21 11:12 ` Oleg Nesterov
2010-07-20 14:21 ` Q: mutlithreaded tracees && clone/exit Jan Kratochvil
2010-07-20 15:09 ` Oleg Nesterov
2010-07-20 19:41 ` Roland McGrath
2010-07-21 8:32 ` Oleg Nesterov
2010-07-20 14:43 ` Q: who maintains the STOPPED/RUNNING state? Oleg Nesterov
[not found] ` <y0mk4ophmvn.fsf@fche.csb>
2010-07-21 10:20 ` Oleg Nesterov
2010-07-21 10:51 ` Oleg Nesterov
2010-07-21 17:06 ` Q: multiple inferiors, all-stop && vCont Oleg Nesterov
2010-07-21 20:42 ` Roland McGrath
2010-07-23 17:33 ` Oleg Nesterov
2010-07-26 14:30 ` Oleg Nesterov
2010-07-26 16:06 ` Oleg Nesterov
2010-07-28 18:19 ` gdbstub initial code, another approach Oleg Nesterov
2010-07-29 21:38 ` Frank Ch. Eigler
2010-07-30 13:00 ` Oleg Nesterov
2010-07-30 13:16 ` Frank Ch. Eigler
2010-07-30 15:01 ` Oleg Nesterov
2010-07-30 13:25 ` Jan Kratochvil
2010-07-30 14:44 ` Oleg Nesterov
2010-07-30 15:20 ` Jan Kratochvil
2010-08-02 12:54 ` Oleg Nesterov
2010-08-03 13:55 ` Jan Kratochvil
2010-07-30 17:59 ` Tom Tromey
2010-08-02 18:25 ` Oleg Nesterov
2010-08-02 23:54 ` Jan Kratochvil
2010-08-03 12:27 ` Q: %Stop && gdb crash Oleg Nesterov
2010-08-03 13:17 ` Oleg Nesterov
2010-08-03 19:57 ` Kevin Buettner
2010-08-04 19:42 ` Oleg Nesterov
2010-08-04 23:32 ` Kevin Buettner
2010-08-05 18:24 ` Oleg Nesterov
2010-08-03 13:36 ` Jan Kratochvil
2010-08-03 15:09 ` Oleg Nesterov [this message]
2010-08-03 12:39 ` Q: multiple inferiors, all-stop && vCont Jan Kratochvil
2010-08-03 14:32 ` Oleg Nesterov
2010-08-03 15:55 ` Jan Kratochvil
2010-08-03 16:56 ` Oleg Nesterov
2010-08-03 18:37 ` Jan Kratochvil
2010-08-18 17:07 ` Jan Kratochvil
2010-08-18 19:22 ` Roland McGrath
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20100803150656.GA8043@redhat.com \
--to=oleg@redhat.com \
--cc=archer@sourceware.org \
--cc=jan.kratochvil@redhat.com \
--cc=roland@redhat.com \
--cc=utrace-devel@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).