Re: [Qemu-devel] [PATCH 13/13] target-ppc: Give a meaningful error if too many threads are specified

[David Gibson <dwg@au1.ibm.com>]

On Thu, Dec 13, 2012 at 01:57:16PM +0100, Alexander Graf wrote:
> 
> On 04.12.2012, at 04:11, David Gibson wrote:
> 
> > On Tue, Dec 04, 2012 at 01:42:17PM +1100, David Gibson wrote:
> >> From: Mike Qiu <qiudayu@linux.vnet.ibm.com>
> > 
> > Oops, messed this one up, build error for user only builds.  Fixed
> > version below.
> > 
> > From d2cc6bcee4737647c4bbbf65d3c0129d4a119dd3 Mon Sep 17 00:00:00 2001
> > From: Mike Qiu <qiudayu@linux.vnet.ibm.com>
> > Date: Tue, 4 Dec 2012 10:52:14 +1100
> > Subject: [PATCH] target-ppc: Give a meaningful error if too many threads are
> > specified
> > 
> > Currently the target-ppc tcg code only supports a single thread.  You can
> > specify more, but they're treated identically to multiple cores.  On KVM
> > we obviously can't support more threads than the hardware; if more are
> > specified it will cause strange and cryptic errors.
> > 
> > This patch clarifies the situation by giving a simple meaningful error if
> > more threads are specified than we can support.
> > 
> > Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> > target-ppc/translate_init.c |   12 ++++++++++++
> > 1 file changed, 12 insertions(+)
> > 
> > diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c
> > index dba572f..bb054a7 100644
> > --- a/target-ppc/translate_init.c
> > +++ b/target-ppc/translate_init.c
> > @@ -28,6 +28,7 @@
> > #include <kvm.h>
> > #include "kvm_ppc.h"
> > #include "arch_init.h"
> > +#include "cpus.h"
> > 
> > //#define PPC_DUMP_CPU
> > //#define PPC_DEBUG_SPR
> > @@ -10037,6 +10038,10 @@ static int ppc_fixup_cpu(CPUPPCState *env)
> > 
> > int cpu_ppc_register_internal (CPUPPCState *env, const ppc_def_t *def)
> > {
> > +#if !defined(CONFIG_USER_ONLY)
> > +    int max_smt = kvmppc_smt_threads();
> 
> What if I am using TCG on PPC?

Then the stub version of kvmppc_smt_threads() returns 1, and since the
PPC TCG doesn't do any SMT emulation, that would seem to be correct...

-- 
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