Re: [Qemu-devel] [PATCH v2 09/24] numa: add check that board supports cpu_index to node mapping

[Eduardo Habkost]

On Wed, May 03, 2017 at 06:19:50PM +0200, Igor Mammedov wrote:
> On Wed, 3 May 2017 12:04:29 -0300
> Eduardo Habkost <address@hidden> wrote:
> 
> > On Wed, May 03, 2017 at 02:57:03PM +0200, Igor Mammedov wrote:
> > > Default node mapping initialization already checks that board
> > > supports cpu_index to node mapping and refuses to start if
> > > it's not supported. Do the same for explicitly provided
> > > mapping "-numa node,cpus=..."
> > > 
> > > Signed-off-by: Igor Mammedov <address@hidden>
> > > ---
> > >  numa.c | 13 ++++++++++---
> > >  1 file changed, 10 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/numa.c b/numa.c
> > > index ab1661d..b517870 100644
> > > --- a/numa.c
> > > +++ b/numa.c
> > > @@ -140,10 +140,12 @@ uint32_t numa_get_node(ram_addr_t addr, Error 
> > > **errp)
> > >      return -1;
> > >  }
> > >  
> > > -static void numa_node_parse(NumaNodeOptions *node, QemuOpts *opts, Error 
> > > **errp)
> > > +static void numa_node_parse(MachineState *ms, NumaNodeOptions *node,
> > > +                            QemuOpts *opts, Error **errp)
> > >  {
> > >      uint16_t nodenr;
> > >      uint16List *cpus = NULL;
> > > +    MachineClass *mc = MACHINE_GET_CLASS(ms);
> > >  
> > >      if (node->has_nodeid) {
> > >          nodenr = node->nodeid;
> > > @@ -162,6 +164,10 @@ static void numa_node_parse(NumaNodeOptions *node, 
> > > QemuOpts *opts, Error **errp)
> > >          return;
> > >      }
> > >  
> > > +    if (!mc->cpu_index_to_instance_props) {
> > > +        error_report("CPUs to NUMA node mapping isn't supported");
> > > +        exit(1);
> > > +    }  
> > 
> > The error message sounds very confusing me. Maybe this could
> > become just: "NUMA is not supported by the %s machine-type"?
> If I replace this specific error message with a generic one and do
> the same in 5/24, it will be harder for us/user to figure out
> where exactly error happened.

I don't think we need to change the message in 5/24 if we change
this one.

> 
> Would be following clearer:
> "option -numa node,cpus= is not supported by the %s machine-type"

It would work if this was really the case. But the error message
is unconditional here, appearing even if cpus= is not set:

  $ qemu-system-x86_64 -m 1G -smp 1 -numa node,mem=1G -machine none
  qemu-system-x86_64: -numa node,mem=1G: CPUs to NUMA node mapping isn't 
supported

-- 
Eduardo