Re: [Xen-devel] [RFC PATCH v3 01/24] NUMA: Make number of NUMA nodes configurable

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Jul 18, 2017 at 06:52:11PM +0100, Julien Grall wrote:
> Hi,
> 
> On 18/07/17 16:29, Wei Liu wrote:
> > On Tue, Jul 18, 2017 at 05:11:23PM +0530, vijay.kilari@xxxxxxxxx wrote:
> > > From: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxx>
> > > 
> > > Introduce NR_NODES config option to specify number
> > > of NUMA nodes supported. By default value is set at
> > > 64 for x86 and 8 for arm. Dropped NODES_SHIFT macro.
> > > 
> > > Also move NR_NODE_MEMBLKS from asm-x86/acpi.h to xen/numa.h
> > > 
> > > Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxx>
> > > ---
> > >  xen/arch/Kconfig           | 7 +++++++
> > >  xen/include/asm-x86/acpi.h | 1 -
> > >  xen/include/asm-x86/numa.h | 2 --
> > >  xen/include/xen/config.h   | 1 +
> > >  xen/include/xen/numa.h     | 7 ++-----
> > >  5 files changed, 10 insertions(+), 8 deletions(-)
> > > 
> > > diff --git a/xen/arch/Kconfig b/xen/arch/Kconfig
> > > index cf0acb7..9c2a4e2 100644
> > > --- a/xen/arch/Kconfig
> > > +++ b/xen/arch/Kconfig
> > > @@ -6,3 +6,10 @@ config NR_CPUS
> > >   default "128" if ARM
> > >   ---help---
> > >     Specifies the maximum number of physical CPUs which Xen will support.
> > > +
> > > +config NR_NODES
> > > + int "Maximum number of NUMA nodes"
> > > + default "64" if X86
> > > + default "8" if ARM
> > > + ---help---
> > > +   Specifies the maximum number of NUMA nodes which Xen will support.
> > 
> > Since this can now be specified by user but the definition of
> > NUMA_NO_NODE is  not changed, I think you need to sanitise the value
> > provided somewhere.
> > 
> > Maybe introduce a build time check? There are some examples in tree. See
> > cpuid.c:build_assertions.
> 
> You can do bound-checking in Kconfig:
> 
> range 1 254
> 

Oh, good to know. Yes this is the way to go.

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