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Date: Wed, 22 Aug 2012 17:58:43 +0200
From: Martin Kletzander <mkletzan@redhat.com>
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Subject: Re: [Qemu-devel] Bug in option parsing
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To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Jason Baron <jbaron@redhat.com>, qemu-devel@nongnu.org

On 08/22/2012 05:15 PM, Jan Kiszka wrote:
> On 2012-08-22 17:05, Martin Kletzander wrote:
>> Hi everybody,
>>
>> while coding the support for Jason's dump-guest-core option I realized
>> there is (probably) a problem with the way QEMU parses additional
>> machine options ('dump-guest-core', 'kvm_shadow_mem' etc.). Running QEMU
>> with option to -machine works ok, but using '-M' (as libvirt does) works
>> only w/o additional options, otherwise it ends in an error (the whole
>> string is probably parsed as a machine name).
>>
>> Is '-M' so obsolete it shouldn't be used at all or is it just an bug? We
>> still use '-M' everywhere I know and '-machine' isn't compatible with
>> older versions and different builds of QEMU.
>>
>> Should I file a bug or do we have to drop '-M' for this situations?
> 
> If libvirt uses -M just like -machine, i.e. with more than a machine
> name, that would be a libvirt bug (but that would have been noticed much
> earlier - did you patch something?). QEMU only keeps -M <machine-name>
> around to please existing users that didn't switch yet. It is NOT an
> alias for -machine.
> 

There is no option *yet* that libvirt would like to use as an additional
option for machine type, but I'm working on the first one and I've hit this.

So your suggestion would be to use -machine wherever it's possible and
fallback to -M only when -machine is not supported?

Martin