From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from [140.186.70.92] (port=50887 helo=eggs.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1OCxVG-0005Z3-5I
	for qemu-devel@nongnu.org; Fri, 14 May 2010 12:12:48 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69)
	(envelope-from <avi@redhat.com>) id 1OCxVE-00014P-8r
	for qemu-devel@nongnu.org; Fri, 14 May 2010 12:12:46 -0400
Received: from mx1.redhat.com ([209.132.183.28]:39813)
	by eggs.gnu.org with esmtp (Exim 4.69)
	(envelope-from <avi@redhat.com>) id 1OCxVE-000142-0u
	for qemu-devel@nongnu.org; Fri, 14 May 2010 12:12:44 -0400
Message-ID: <4BED7676.8060707@redhat.com>
Date: Fri, 14 May 2010 19:12:38 +0300
From: Avi Kivity <avi@redhat.com>
MIME-Version: 1.0
References: <cover.1273843151.git.jan.kiszka@siemens.com>
In-Reply-To: <cover.1273843151.git.jan.kiszka@siemens.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Subject: [Qemu-devel] Re: [PATCH 0/8] Basic device state visualization
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Markus Armbruster <armbru@redhat.com>, Anthony Liguori <aliguori@us.ibm.com>, Juan Quintela <quintela@redhat.com>, qemu-devel@nongnu.org, Luiz Capitulino <lcapitulino@redhat.com>

On 05/14/2010 04:20 PM, Jan Kiszka wrote:
> While recently fixing the SCSI reset issues, I once again had the need
> for displaying the state of involved devices. So far the common approach
> is to attach gdb to qemu (or even inject some printf). But that time I
> hacked up a 30-minute patch to dump the vmstate of any (fully converted)
> qdev device.
>    

Wonderful! may even motivate some more qmp conversions.

> This series now lays the ground for more sophisticated visulization. It
> adds the monitor command 'device_show<qdev-path>', freezes the vmstate
> of the addressed device, sticks it into a QMP dict, and either transmit
> this via QMP or pretty-prints it on a monitor console. Some example:
>
> (qemu) device_show /i440FX-pcihost/pci.0/piix3-usb-uhci
> dev: piix3-usb-uhci, id ""
>    dev.
>      version_id:         00000002
>      config:             a0 7d d1 00 00 00 00 00 - b0 7e d1 00 00 00 00 00
>                          ...
>      irq_state:          00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00
>    num_ports_vmstate:    02
>    ports[00].
>        ctrl:             0083
>    ports[01].
>        ctrl:             0080
>    cmd:                  00c1
>    status:               0000
>    intr:                 0000
>    frnum:                0077
>    fl_base_addr:         0fffc000
>    sof_timing:           40
>    status2:              00
>    frame_timer:          0000000000cb2bd0
>
> Basically, this is the level of support I recently saw in a
> demonstration of some commercial simulator as well. We are just lacking
> support for the yet unconverted devices. And I think we can even do
> better on the long term, e.g. by annotating state variables that contain
> flags, or by pretty-printing buffers like the PCI config space, or...
>
>    

Will be interesting to pass these annotations via qmp as well.

> Let's give this a start, I bet it will be helpful while adding complex
> device models like AHCI or EHCI. Looking forward to feedback!
>    

I'd like to see qmp command documentation for this.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.