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Date: Tue, 30 Apr 2013 17:14:00 +0200
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Subject: Re: [Qemu-devel] [PATCH 3/5] add cpu_model to QEMUMachine
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: aliguori@us.ibm.com, Eduardo Habkost <ehabkost@redhat.com>, qemu-devel@nongnu.org, anthony.perard@citrix.com, pbonzini@redhat.com, afaerber@suse.de

On Tue, 30 Apr 2013 15:54:34 +0100
Peter Maydell <peter.maydell@linaro.org> wrote:

> On 30 April 2013 15:30, Eduardo Habkost <ehabkost@redhat.com> wrote:
> > My concern is that we already have a QEMUMachineInitArgs.cpu_model
> > field, and now QEMUMachine.cpu_model and QEMUMachineInitArgs.cpu_model
> > are redundant.
> >
> > To make it worse, both variables can disagree with each other because we
> > have other code that set QEMUMachineInitArgs.cpu_model outside of
> > main():
> >
> > hw/arm/realview.c:338:        args->cpu_model = "arm926";
> > hw/arm/realview.c:346:        args->cpu_model = "arm11mpcore";
> > hw/arm/realview.c:354:        args->cpu_model = "cortex-a8";
> > hw/arm/realview.c:362:        args->cpu_model = "cortex-a9";
> > hw/arm/versatilepb.c:189:        args->cpu_model = "arm926";
> >
> > ARM doesn't have CPU hotplug, but this is still a bug waiting to happen.
> 
> This ARM code is just borrowing the cpu_model field as a convenient
> place to stash the default value for the board. There are other
> ARM boards which do a similar thing but in a purely local variable
> (eg vexpress)...
yes, patch addresses Eduardo's concern about not setting cpu_model of machine args
anywhere else except of main. And later we could cleanup machine args usage
and default cpu_models for all targets.

> 
> I think really if you want to know what the current CPU model
> is you need to fish the relevant QOM qbject out from somewhere
> at runtime.

Ideally that QOM object would be QOMifyed QEMUMachine, but we are not there yet.

>
> -- PMM
>