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Re: [Xen-devel] [RFC PATCH v2 09/25] ARM: NUMA: Add existing ARM numa code under CONFIG_NUMA

Hi Vijay,

On 28/03/17 16:53, vijay.kilari@xxxxxxxxx wrote:
From: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxx>

Right now CONFIG_NUMA is not enabled for ARM and
existing code in asm-arm/numa.h is for !CONFIG_NUMA.
Hence put this code under #ifndef CONFIG_NUMA.

This help to make this changes work when CONFIG_NUMA
is not enabled.

But you always turn NUMA on by default (see patch #24) and there is no possibility to turn off NUMA.

Also define NODES_SHIFT macro for ARM to value 2.
This limits number of NUMA nodes supported to 4.
There is not hard restrictions on this value set to 2.

Again, why only 2 when x86 is supporting 6?

Furthermore, this is not related to this patch itself and should be part of separate patch.

Lastly, why don't you move that to a Kconfig allowing the user to configure the number of Nodes?

Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxx>
 xen/include/asm-arm/numa.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/xen/include/asm-arm/numa.h b/xen/include/asm-arm/numa.h
index 53f99af..924bfc0 100644
--- a/xen/include/asm-arm/numa.h
+++ b/xen/include/asm-arm/numa.h
@@ -3,6 +3,10 @@

 typedef uint8_t nodeid_t;

+/* Limit number of NUMA nodes supported to 4 */
+#define NODES_SHIFT 2

Why this is not covered by CONFIG_NUMA?

+#ifndef CONFIG_NUMA
 /* Fake one node for now. See also node_online_map. */
 #define cpu_to_node(cpu) 0
 #define node_to_cpumask(node)   (cpu_online_map)
@@ -16,6 +20,7 @@ static inline __attribute__((pure)) nodeid_t 
phys_to_nid(paddr_t addr)
 #define node_spanned_pages(nid) (total_pages)
 #define node_start_pfn(nid) (pdx_to_pfn(frametable_base_pdx))
 #define __node_distance(a, b) (20)
+#endif /* CONFIG_NUMA */

 static inline unsigned int arch_get_dma_bitsize(void)


Julien Grall

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