Re: [Qemu-ppc] [PATCH v2 4/7] ppc: open code cpu creation for machine types

[Greg Kurz]

On Sat, 2 Jul 2016 13:36:22 +0530
Bharata B Rao <address@hidden> wrote:

> On Sat, Jul 02, 2016 at 12:41:48AM +0200, Greg Kurz wrote:
> > If we want to generate cpu_dt_id in the machine code, this must occur
> > before the cpu gets realized. We must open code the cpu creation to be
> > able to do this.
> > 
> > This patch just does that. It borrows some lines from previous work
> > from Bharata to handle the feature parsing.
> > 
> > Signed-off-by: Greg Kurz <address@hidden>
> > ---
> >  hw/ppc/ppc.c |   39 ++++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 38 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
> > index dc3d214009c5..57f4ddd073d0 100644
> > --- a/hw/ppc/ppc.c
> > +++ b/hw/ppc/ppc.c
> > @@ -32,6 +32,7 @@
> >  #include "sysemu/cpus.h"
> >  #include "hw/timer/m48t59.h"
> >  #include "qemu/log.h"
> > +#include "qapi/error.h"
> >  #include "qemu/error-report.h"
> >  #include "hw/loader.h"
> >  #include "sysemu/kvm.h"
> > @@ -1353,5 +1354,41 @@ PowerPCCPU *ppc_get_vcpu_by_dt_id(int cpu_dt_id)
> > 
> >  PowerPCCPU *ppc_cpu_init(const char *cpu_model)
> >  {
> > -    return POWERPC_CPU(cpu_generic_init(TYPE_POWERPC_CPU, cpu_model));
> > +    PowerPCCPU *cpu;
> > +    CPUClass *cc;
> > +    ObjectClass *oc;
> > +    gchar **model_pieces;
> > +    Error *err = NULL;
> > +
> > +    model_pieces = g_strsplit(cpu_model, ",", 2);
> > +    if (!model_pieces[0]) {
> > +        error_report("Invalid/empty CPU model name");
> > +        return NULL;
> > +    }
> > +
> > +    oc = cpu_class_by_name(TYPE_POWERPC_CPU, model_pieces[0]);
> > +    if (oc == NULL) {
> > +        error_report("Unable to find CPU definition: %s", model_pieces[0]);
> > +        return NULL;
> > +    }
> > +
> > +    cpu = POWERPC_CPU(object_new(object_class_get_name(oc)));
> > +
> > +    cc = CPU_CLASS(oc);
> > +    cc->parse_features(CPU(cpu), model_pieces[1], &err);  
> 
> Igor is working on a patchset to convert -cpu features into global properties.
> IIUC, after that patchset, it is not recommended to parse the -cpu features
> for every CPU but do it only once.
> 

cpu_generic_init() in the current code also does the parsing, and as the title
says, this patch is just about open coding the creation. I don't want to
change behavior yet.

But yes, I agree that we should only parse features once and I'll be more than
happy to fix this in a followup patch, based on Igor's work.

In the meantime, maybe I can add a comment stating that the parsing should go
away ?

> That is what I attempted here in the context of supporting compat cpu type
> for pseries-2.7:
> 
> https://www.mail-archive.com/address@hidden/msg381660.html
> 

Yeah and this is where I borrowed some lines. :)

> Regards,
> Bharata.
> 

Cheers.

--
Greg