Re: [Qemu-devel] [PATCH] spapr: move registration of "host" CPU core type to machine code

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Sep 26, 2017 at 09:19:28AM +0200, Greg Kurz wrote:
> On Tue, 26 Sep 2017 12:57:39 +1000
> David Gibson <david@gibson.dropbear.id.au> wrote:
> 
> > On Mon, Sep 25, 2017 at 11:47:33AM +0200, Greg Kurz wrote:
> > > The CPU core abstraction belongs to the machine code. This also gets
> > > rid of some code duplication.
> > > 
> > > Signed-off-by: Greg Kurz <groug@kaod.org>
> > > ---
> > > 
> > > hw/ppc/spapr_cpu_core.h is also included elsewhere in target/ppc/kvm.c
> > > but this is already handled by the following cleanup patch:  
> > 
> > I don't really see what the advantage of this is.  As others have
> > pointed out it leads to the host type being registered very late,
> > which could cause problems.
> > 
> 
> Well, the goal was to consolidate the code to register sPAPRCPUCore types in
> the spapr code, instead of open-coding it in spapr_cpu_core.c and kvm.c... 
> 
> But now I realize that delaying the registration even more is a bad idea. And,
> the other way round, registering a static type earlier as asked by Igor would
> require all parent types to be already registered, which seems to be impossible
> to guarantee with the current code.
> 
> Maybe we could at least have kvm_ppc_register_host_cpu_type() to call a
> function in spapr_cpu_core.c instead of duplicating the registration
> code ?

I think that sounds like a better idea.  It's still a little bodgy
with the abstraction boundaries, but I think that's unavoidable: this
fundamentally depends on both KVM's presence and use of the PAPR
machine type.  Whichever place we put it, you could argue it belongs
better in the other one.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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