From: Florian Weimer <fweimer@redhat.com>
To: Stefan Hajnoczi via Gdb <gdb@sourceware.org>
Cc: Stefan Hajnoczi <stefanha@redhat.com>,
tom@tromey.com, qemu-devel@nongnu.org, pedro@palves.net,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: How to backtrace an separate stack?
Date: Mon, 07 Mar 2022 15:49:37 +0100 [thread overview]
Message-ID: <87sfrtakce.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <YiCk+NNtAGQPhyK5@stefanha-x1.localdomain> (Stefan Hajnoczi via Gdb's message of "Thu, 3 Mar 2022 11:22:32 +0000")
* Stefan Hajnoczi via Gdb:
> The QEMU emulator uses coroutines with separate stacks. It can be
> challenging to debug coroutines that have yielded because GDB is not
> aware of them (no thread is currently executing them).
>
> QEMU has a GDB Python script that helps. It "creates" a stack frame for
> a given coroutine by temporarily setting register values and then using
> the "bt" command. This works on a live process under ptrace control but
> not for coredumps where registers can't be set.
>
> Here is the script (or see the bottom of this email for an inline copy
> of the relevant code):
> https://gitlab.com/qemu-project/qemu/-/blob/master/scripts/qemugdb/coroutine.py
>
> I hoped that "select-frame address ADDRESS" could be used instead so
> this would work on coredumps too. Unfortunately "select-frame" only
> searches stack frames that GDB is already aware of, so it cannot be used
> to backtrace coroutine stacks.
>
> Is there a way to backtrace a stack at an arbitrary address in GDB?
I'm a bit surprised by this. Conceptually, why would GDB need to know
about stack boundaries? Is there some heuristic to detect broken
frames?
Thanks,
Florian
next prev parent reply other threads:[~2022-03-07 14:49 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-03 11:22 Stefan Hajnoczi
2022-03-07 10:49 ` Pedro Alves
2022-03-08 9:47 ` Stefan Hajnoczi
2022-03-07 14:49 ` Florian Weimer [this message]
2022-03-07 17:30 ` Tom Tromey
2022-03-09 10:06 ` Florian Weimer
2022-03-09 19:50 ` Tom Tromey
2022-03-07 16:58 ` Tom Tromey
2022-03-07 17:18 ` Pedro Alves
2022-03-08 8:43 ` Stefan Hajnoczi
2022-03-14 20:30 ` Tom Tromey
2022-03-15 14:17 ` Stefan Hajnoczi
2022-03-18 21:13 ` Tom Tromey
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=87sfrtakce.fsf@oldenburg.str.redhat.com \
--to=fweimer@redhat.com \
--cc=dgilbert@redhat.com \
--cc=gdb@sourceware.org \
--cc=pedro@palves.net \
--cc=qemu-devel@nongnu.org \
--cc=stefanha@redhat.com \
--cc=tom@tromey.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).