Re: [Xen-devel] [PATCH] xen: arm: ignore CPUs which are not marked available in the DT

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 24/07/14 11:40, Ian Campbell wrote:
> On Thu, 2014-07-24 at 11:36 +0100, Julien Grall wrote:
> > Hi Ian,
> >
> > On 23/07/14 19:36, Ian Campbell wrote:
> > > On Wed, 2014-07-23 at 18:15 +0100, Julien Grall wrote:
> > > > On 07/23/2014 05:45 PM, Ian Campbell wrote:
> > > > > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > > > > ---
> > > > >    xen/arch/arm/smpboot.c |    3 +++
> > > > >    1 file changed, 3 insertions(+)
> > > > >
> > > > > diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c
> > > > > index cf149da..4b0a738 100644
> > > > > --- a/xen/arch/arm/smpboot.c
> > > > > +++ b/xen/arch/arm/smpboot.c
> > > > > @@ -134,6 +134,9 @@ void __init smp_init_cpus(void)
> > > > >            if ( !dt_device_type_is_equal(cpu, "cpu") )
> > > > >                continue;
> > > > >
> > > > > +        if ( !dt_device_is_available(cpu) )
> > > > > +            continue;
> > > > > +
> > > > I can't find a such things on the Linux device tree bindings.
> > > status is a generic property which is common to all nodes, it comes from
> > > ePAPR.
> > >
> > > >    Do you
> > > > have a use case where CPU are marked disabled?
> > > I use it locally when booting with models -- it allows me to turn off
> > > cpus in the base .dts file using a wrapper instead of having to edit the
> > > original.
> > I read the ePAPR and the property status on CPU node. AFAIU, the
> > property doesn't have this meaning for a such node.
> >
> > This property means the CPU is in quiescent state and property to bring
> > up the CPU is provides in the device tree node.
> >
> > Section 5.5.2.2:
> >
> > Before starting a client program on the boot cpu, the boot program shall
> > set certain properties in the
> > device tree passed to the client as follows:
> > â Each secondary CPUâs cpu node shall have a status property with a
> > value of âdisabledâ.
> Oh well, it was only a convenience for me anyway.
> Ian
Could we add a property xen,status for debugging (i.e when Xen is 
compiled with debug=y)? So we don't collapse with the actual property if 
someone decide to implement it in the bootloader.
Regards,

--
Julien Grall

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