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Date: Thu, 2 Jun 2016 12:06:59 +0200
From: Igor Mammedov <imammedo@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH RFC 6/8] cpu: use
 CPUClass->parse_features() as convertor to global properties
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To: Eduardo Habkost <ehabkost@redhat.com>
Cc: peter.maydell@linaro.org, mark.cave-ayland@ilande.co.uk, qemu-devel@nongnu.org, blauwirbel@gmail.com, qemu-arm@nongnu.org, pbonzini@redhat.com, rth@twiddle.net

On Wed, 1 Jun 2016 15:54:50 -0300
Eduardo Habkost <ehabkost@redhat.com> wrote:

> On Wed, Jun 01, 2016 at 06:37:28PM +0200, Igor Mammedov wrote:
> > Currently CPUClass->parse_features() is used to parse
> > -cpu features string and set properties on created CPU
> > instances.
> > 
> > But considering that features specified -cpu apply to
> > every created CPU instance, it doesn't make sence to
> > parse the same features string for every CPU created.
> > It also makes every target that cares about parsing
> > features string explicitly call CPUClass->parse_features()
> > parser, which gets in a way if we consider using
> > generic device_add for CPU hotplug as device_add
> > has not a clue about CPU specific hooks.
> > 
> > Turns out we can use global properties mechanism to set
> > properties on every created Device instance for a given
> > type. That way it's possible to convert CPU features
> > into a set of global properties for specified by
> >  -cpu cpu_model and common Device.device_post_init()
> > will apply them to every cpu model model automaticaaly
> > regardless whether it's manually created CPU or CPU
> > created with help of device_add.
> > 
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > ---
> [...]
> > -static void cpu_common_parse_features(CPUState *cpu, char
> > *features, +static void cpu_common_parse_features(const char
> > *typename, char *features, Error **errp)
> >  {
> >      char *featurestr; /* Single "key=value" string being parsed */
> >      char *val;
> > -    Error *err = NULL;
> > +    static bool cpu_globals_initialized;
> > +
> > +    if (cpu_globals_initialized) {
> > +        return;
> > +    }
> 
> Should we replace this with assert(!cpu_globals_initialized)
> after applying patch 8/8?
assert might potentially break cpu_init() users, so I went safest route
here.