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

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Tue, 20 Dec 2011, Stefan Hajnoczi wrote:

> 2011/12/20 Âçæaware <250716708@xxxxxx>:
> > ÂÂÂ IÂwant 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.
> > ÂÂÂ But I am not very clear about the structure of the qemu-dm source code.
> > AlthoughÂobserving the output of execution is the straightforward way, high
> > frequency of printf and re-compling is too incovenient to put into effect.
>
> Please keep qemu-devel@xxxxxxxxxx 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

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