Re: [Xen-devel] [RFC PATCH v3 10/24] NUMA: Allow numa initialization with DT

[Julien Grall <julien.grall@xxxxxxx>]

Hi Vijay,

On 20/07/17 11:28, Vijay Kilari wrote:
> On Wed, Jul 19, 2017 at 11:28 PM, Julien Grall <julien.grall@xxxxxxx> wrote:
> > Hi Vijay,
> >
> > On 18/07/17 12:41, vijay.kilari@xxxxxxxxx wrote:
> > > From: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxx>
> > >
> > > The common code allows numa initialization only when
> > > ACPI_NUMA config is enabled. Allow initialization when
> > > NUMA config is enabled for DT.
> > >
> > > In this patch, along with acpi_numa, check for acpi_disabled
> > > is added.
> > >
> > > Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxx>
> > > ---
> > >  xen/common/numa.c | 4 +---
> > >  1 file changed, 1 insertion(+), 3 deletions(-)
> > >
> > > diff --git a/xen/common/numa.c b/xen/common/numa.c
> > > index 74c4697..5e985d2 100644
> > > --- a/xen/common/numa.c
> > > +++ b/xen/common/numa.c
> > > @@ -324,7 +324,7 @@ static int __init numa_scan_nodes(paddr_t start,
> > > paddr_t end)
> > >      for ( i = 0; i < MAX_NUMNODES; i++ )
> > >          cutoff_node(i, start, end);
> > >
> > > -    if ( acpi_numa <= 0 )
> > > +    if ( !acpi_disabled && acpi_numa <= 0 )
> >
> > I am struggling to understand this change. Likely you want to similar
> > variable for DT to say NUMA is available or this has failed.
> Yes, without this check for acpi_disabled, when booting with DT, the check
> acpi_numa <= 0 is true and does not allow numa initialization.
>
> > This also change quite a bit the semantic for x86 because, you will now
> > continue if acpi_disabled and acpi_numa = 0. The code seems to allow it, but
> > I don't know if we support it.
> Yes, but prior to this patch, x86 is assuming that acpi_disabled is
> false by checking
> only for acpi_numa <=0.
101 of the contributor: make sure the commit message is meaningful to 
understand your changes.
> The other solution is create a arch wrapper and call this from here.
I suggested another solution but you seem to have ignored it... You can 
rename acpi_numa into something more generic and use it also for DT to 
detect whether it is possible to use NUMA.
Cheers,

--
Julien Grall

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