From: "Daniel P. Berrangé" <berrange@redhat.com>
To: Steven Sistare <steven.sistare@oracle.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
"Juan Quintela" <quintela@redhat.com>,
qemu-devel@nongnu.org,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
"Alex Bennée" <alex.bennee@linaro.org>,
"Alex Williamson" <alex.williamson@redhat.com>,
"Stefan Hajnoczi" <stefanha@redhat.com>,
"Marc-André Lureau" <marcandre.lureau@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>,
"Markus Armbruster" <armbru@redhat.com>
Subject: Re: [PATCH V1 12/32] vl: pause option
Date: Fri, 31 Jul 2020 11:07:42 +0100 [thread overview]
Message-ID: <20200731100742.GA3641941@redhat.com> (raw)
In-Reply-To: <36036b5f-4e63-4287-a8e6-499732f54689@oracle.com>
On Thu, Jul 30, 2020 at 02:11:19PM -0400, Steven Sistare wrote:
> On 7/30/2020 12:20 PM, Eric Blake wrote:
> > On 7/30/20 10:14 AM, Steve Sistare wrote:
> >> Provide the -pause command-line parameter and the QEMU_PAUSE environment
> >> variable to briefly pause QEMU in main and allow a developer to attach gdb.
> >> Useful when the developer does not invoke QEMU directly, such as when using
> >> libvirt.
> >
> > How would you set this option with libvirt?
>
> Add -pause in the qemu args in the xml.
>
> > It feels like you are trying to reinvent something that is already well-documented:
> >
> > https://www.berrange.com/posts/2011/10/12/debugging-early-startup-of-kvm-with-gdb-when-launched-by-libvirtd/
>
> Too many steps to reach BINGO for my taste. Easier is better. Also, in our shop we start qemu
> in other ways, such as via services.
A "sleep" is a pretty crude & unreliable way to get into debugging
though. It is racy for a start, but also QEMU has a bunch of stuff
that runs via ELF constructors before main() even starts.
So I feel like the thing that starts QEMU is better placed to provide
a way in for debugging.
eg the service launcher can send SIGSTOP to the child process immediately
before the execve(qemu) call.
Now user can attach with the debugger, allow execution to continue,
and has ability to debug *everything* right from the ELF constructors
onwards into main() and all that follows.
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
next prev parent reply other threads:[~2020-07-31 10:11 UTC|newest]
Thread overview: 118+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-30 15:14 [PATCH V1 00/32] Live Update Steve Sistare
2020-07-30 15:14 ` [PATCH V1 01/32] savevm: add vmstate handler iterators Steve Sistare
2020-09-11 16:24 ` Dr. David Alan Gilbert
2020-09-24 21:43 ` Steven Sistare
2020-09-25 9:07 ` Dr. David Alan Gilbert
2020-07-30 15:14 ` [PATCH V1 02/32] savevm: VM handlers mode mask Steve Sistare
2020-07-30 15:14 ` [PATCH V1 03/32] savevm: QMP command for cprsave Steve Sistare
2020-07-30 16:12 ` Eric Blake
2020-07-30 17:52 ` Steven Sistare
2020-09-11 16:43 ` Dr. David Alan Gilbert
2020-09-25 18:43 ` Steven Sistare
2020-09-25 22:22 ` Steven Sistare
2020-07-30 15:14 ` [PATCH V1 04/32] savevm: HMP Command " Steve Sistare
2020-09-11 16:57 ` Dr. David Alan Gilbert
2020-09-24 21:44 ` Steven Sistare
2020-09-25 9:26 ` Dr. David Alan Gilbert
2020-07-30 15:14 ` [PATCH V1 05/32] savevm: QMP command for cprload Steve Sistare
2020-07-30 16:14 ` Eric Blake
2020-07-30 18:00 ` Steven Sistare
2020-09-11 17:18 ` Dr. David Alan Gilbert
2020-09-24 21:49 ` Steven Sistare
2020-07-30 15:14 ` [PATCH V1 06/32] savevm: HMP Command " Steve Sistare
2020-07-30 15:14 ` [PATCH V1 07/32] savevm: QMP command for cprinfo Steve Sistare
2020-07-30 16:17 ` Eric Blake
2020-07-30 18:02 ` Steven Sistare
2020-07-30 15:14 ` [PATCH V1 08/32] savevm: HMP " Steve Sistare
2020-09-11 17:27 ` Dr. David Alan Gilbert
2020-09-24 21:50 ` Steven Sistare
2020-07-30 15:14 ` [PATCH V1 09/32] savevm: prevent cprsave if memory is volatile Steve Sistare
2020-09-11 17:35 ` Dr. David Alan Gilbert
2020-09-24 21:51 ` Steven Sistare
2020-07-30 15:14 ` [PATCH V1 10/32] kvmclock: restore paused KVM clock Steve Sistare
2020-09-11 17:50 ` Dr. David Alan Gilbert
2020-09-25 18:07 ` Steven Sistare
2020-07-30 15:14 ` [PATCH V1 11/32] cpu: disable ticks when suspended Steve Sistare
2020-09-11 17:53 ` Dr. David Alan Gilbert
2020-09-24 20:42 ` Steven Sistare
2020-09-25 9:03 ` Dr. David Alan Gilbert
2020-07-30 15:14 ` [PATCH V1 12/32] vl: pause option Steve Sistare
2020-07-30 16:20 ` Eric Blake
2020-07-30 18:11 ` Steven Sistare
2020-07-31 10:07 ` Daniel P. Berrangé [this message]
2020-07-31 15:18 ` Steven Sistare
2020-07-30 17:03 ` Alex Bennée
2020-07-30 18:14 ` Steven Sistare
2020-07-31 9:44 ` Alex Bennée
2020-09-11 17:59 ` Dr. David Alan Gilbert
2020-09-24 21:51 ` Steven Sistare
2020-07-30 15:14 ` [PATCH V1 13/32] gdbstub: gdb support for suspended state Steve Sistare
2020-09-11 18:41 ` Dr. David Alan Gilbert
2020-09-24 21:51 ` Steven Sistare
2020-07-30 15:14 ` [PATCH V1 14/32] savevm: VMS_RESTART and cprsave restart Steve Sistare
2020-07-30 16:22 ` Eric Blake
2020-07-30 18:14 ` Steven Sistare
2020-09-11 18:44 ` Dr. David Alan Gilbert
2020-09-24 21:44 ` Steven Sistare
2020-07-30 15:14 ` [PATCH V1 15/32] vl: QEMU_START_FREEZE env var Steve Sistare
2020-09-11 18:49 ` Dr. David Alan Gilbert
2020-09-24 21:47 ` Steven Sistare
2020-09-25 15:52 ` Dr. David Alan Gilbert
2020-07-30 15:14 ` [PATCH V1 16/32] oslib: add qemu_clr_cloexec Steve Sistare
2020-09-11 18:52 ` Dr. David Alan Gilbert
2020-07-30 15:14 ` [PATCH V1 17/32] util: env var helpers Steve Sistare
2020-09-11 19:00 ` Dr. David Alan Gilbert
2020-09-24 21:52 ` Steven Sistare
2020-07-30 15:14 ` [PATCH V1 18/32] osdep: import MADV_DOEXEC Steve Sistare
2020-08-17 18:30 ` Steven Sistare
2020-08-17 20:48 ` Alex Williamson
2020-08-17 21:20 ` Steven Sistare
2020-08-17 21:44 ` Alex Williamson
2020-08-18 2:42 ` Alex Williamson
2020-08-19 21:52 ` Steven Sistare
2020-08-24 22:30 ` Alex Williamson
2020-10-08 16:32 ` Steven Sistare
2020-10-15 20:36 ` Alex Williamson
2020-10-19 16:33 ` Steven Sistare
2020-10-26 18:28 ` Steven Sistare
2020-07-30 15:14 ` [PATCH V1 19/32] memory: ram_block_add cosmetic changes Steve Sistare
2020-07-30 15:14 ` [PATCH V1 20/32] vl: add helper to request re-exec Steve Sistare
2020-07-30 15:14 ` [PATCH V1 21/32] exec, memory: exec(3) to restart Steve Sistare
2020-07-30 15:14 ` [PATCH V1 22/32] char: qio_channel_socket_accept reuse fd Steve Sistare
2020-09-15 17:33 ` Dr. David Alan Gilbert
2020-09-15 17:53 ` Daniel P. Berrangé
2020-09-24 21:54 ` Steven Sistare
2020-07-30 15:14 ` [PATCH V1 23/32] char: save/restore chardev socket fds Steve Sistare
2020-07-30 15:14 ` [PATCH V1 24/32] ui: save/restore vnc " Steve Sistare
2020-07-31 9:06 ` Daniel P. Berrangé
2020-07-31 16:51 ` Steven Sistare
2020-07-30 15:14 ` [PATCH V1 25/32] char: save/restore chardev pty fds Steve Sistare
2020-07-30 15:14 ` [PATCH V1 26/32] monitor: save/restore QMP negotiation status Steve Sistare
2020-07-30 15:14 ` [PATCH V1 27/32] vhost: reset vhost devices upon cprsave Steve Sistare
2020-07-30 15:14 ` [PATCH V1 28/32] char: restore terminal on restart Steve Sistare
2020-07-30 15:14 ` [PATCH V1 29/32] pci: export pci_update_mappings Steve Sistare
2020-07-30 15:14 ` [PATCH V1 30/32] vfio-pci: save and restore Steve Sistare
2020-08-06 10:22 ` Jason Zeng
2020-08-07 20:38 ` Steven Sistare
2020-08-10 3:50 ` Jason Zeng
2020-08-19 21:15 ` Steven Sistare
2020-08-20 10:33 ` Jason Zeng
2020-10-07 21:25 ` Steven Sistare
2020-07-30 15:14 ` [PATCH V1 31/32] vfio-pci: trace pci config Steve Sistare
2020-07-30 15:14 ` [PATCH V1 32/32] vfio-pci: improved tracing Steve Sistare
2020-09-15 18:49 ` Dr. David Alan Gilbert
2020-09-24 21:52 ` Steven Sistare
2020-07-30 16:52 ` [PATCH V1 00/32] Live Update Daniel P. Berrangé
2020-07-30 18:48 ` Steven Sistare
2020-07-31 8:53 ` Daniel P. Berrangé
2020-07-31 15:27 ` Steven Sistare
2020-07-31 15:52 ` Daniel P. Berrangé
2020-07-31 17:20 ` Steven Sistare
2020-08-11 19:08 ` Dr. David Alan Gilbert
2020-07-30 17:15 ` Paolo Bonzini
2020-07-30 19:09 ` Steven Sistare
2020-07-30 21:39 ` Paolo Bonzini
2020-07-31 19:22 ` Steven Sistare
2020-07-30 17:49 ` Dr. David Alan Gilbert
2020-07-30 19:31 ` Steven Sistare
2020-08-04 18:18 ` Steven Sistare
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