[Qemu-devel] problem with 'xm save' in xen-3.4

[¤終於aware]

Hi,

    the problem is as follows:(And then, others can't login mostly because of the os' busing and you can't do anything else.)

address@hidden ::三 12月 21::~]$ sudo xm list
Name                                        ID   Mem VCPUs      State   Time(s)
Domain-0                                     0  1748     2     r-----  29396.3
xp-101                                       1   256     1     -b----   4685.8

 

address@hidden ::三 12月 21::~]$ sudo xm save 1 1.save

Message from syslogd@ at Wed Dec 21 10:27:10 2011 ...
xentest kernel: unregister_netdevice: waiting for tap1.0 to become free. Usage count = 1

Message from syslogd@ at Wed Dec 21 10:27:41 2011 ...
xentest last message repeated 3 times
Message from syslogd@ at Wed Dec 21 10:28:52 2011 ...
xentest last message repeated 7 times

.......................

 

------------------ 原始邮件 ------------------

发件人: "Anthony PERARD"<address@hidden>;

发送时间: 2011年12月20日(星期二) 晚上9:48

收件人: "Stefan Hajnoczi"<address@hidden>;

抄送: "¤終於aware"<address@hidden>; "qemu-devel"<address@hidden>; "Stefano Stabellini"<address@hidden>; "Xen Devel"<address@hidden>;

主题: Re: 回复： [Qemu-devel] debuging about qemu-dm in xen 3.4.2

 

On Tue, 20 Dec 2011, Stefan Hajnoczi wrote:

> 2011/12/20 ¤終於aware <address@hidden>:
> >     I want to create a memory snapshot file (such as mm.snap) of current
> > virtual machine and  the mm.snap can be used as a arg of qemu cmd-line for
> > restoring the last memory condition.
> >     But I am not very clear about the structure of the qemu-dm source code.
> > Although observing the output of execution is the straightforward way, high
> > frequency of printf  and re-compling is too incovenient to put into effect.
>
> Please keep address@hidden CCed so others can contribute to the
> discussion.
>
> QEMU only deals with virtual memory when simulating an MMU (for
> ARM-on-x86 system translation).  The device model usually operates on
> physical RAM or bus addresses.
>
> Stefano or Anthony can explain the qemu-dm specifics.  It's still not
> clear to me what you're trying to observe - qemu-dm is not where I'd
> try to observe domain memory under Xen but it's the right place to
> observe emulated devices.

Cced Xen-devel as well.

You can save a domain state using the tool stack (probably `xm save`
with Xen 3.4) and restore it as many time as you want.

To run gdb on qemu-dm, remplace the /usr/lib/xen/bin/qemu-dm by a
script:
#!/bin/sh
exec gdbserver 0.0.0.0:1234 /usr/lib/xen/bin/qemu-dm.bak $@

And run gdb. `target remote localhost 1234` to connect to gdbserver.

With the latest Xen (4.1 and unstable), you can specifie a different
device model in the config file instead of remplacing the default
binary.

Regards,

--
Anthony PERARD