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SubjectRe: x86-64 NODES_SHIFT compile failure.
Dave Jones wrote:
> 4323838215184f5a2f081e0d17b8d60731b03164 added this line to x86's Kconfig..
>
> config NODES_SHIFT
> int
> + range 1 15 if X86_64
> default "6" if X86_64
> default "4" if X86_NUMAQ
> default "3"
>
> Selecting 15 causes:
>
> drivers/base/node.c: In function ‘node_read_distance’:
> drivers/base/node.c:140: error: size of array ‘type name’ is negative
>
> Should the upper limit be reduced to 14 (which compiles), or should
> the BUILD_BUG_ON be changed to somehow cope with this set of changes?
>
> Dave
>

A later patch changed it to 9 which is the current real limit of NODES_SHIFT
(or at least the fully tested limit). I think it might be in Ingo's
sched/latest tree, but here it is again.. (cleaned up with MAXSMP not included.)


Subject: [PATCH 1/1] x86: change maximum NR_CPUS to 4096 and MAX_NUMNODES to 512

* Change the range of NR_CPUS from 2-255 to 2-4096 and change the
range of MAX_NUMNODES (NODES_SHIFT) from 1-32768 to 1-512.

* Alter comment about how much each increment of NR_CPUS consumes.
(This was found by configuring for 256 cpus and then 512 cpus
and dividing the difference by 256.)

Signed-off-by: Mike Travis <travis@sgi.com>
---
arch/x86/Kconfig | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
--- linux-2.6-next.orig/arch/x86/Kconfig
+++ linux-2.6-next/arch/x86/Kconfig
@@ -566,18 +566,18 @@ config IOMMU_HELPER
def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB)

config NR_CPUS
- int "Maximum number of CPUs (2-255)"
- range 2 255
+ int "Maximum number of CPUs (2-4096)"
+ range 2 4096
depends on SMP
default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
default "8"
help
This allows you to specify the maximum number of CPUs which this
- kernel will support. The maximum supported value is 255 and the
+ kernel will support. The maximum supported value is 4096 and the
minimum value which makes sense is 2.

This is purely to save memory - each supported CPU adds
- approximately eight kilobytes to the kernel image.
+ approximately one kilobyte to the kernel image.

config SCHED_SMT
bool "SMT (Hyperthreading) scheduler support"
@@ -969,8 +969,8 @@ config NUMA_EMU
number of nodes. This is only useful for debugging.

config NODES_SHIFT
- int "Max num nodes shift(1-15)"
- range 1 15 if X86_64
+ int "Max num nodes shift(1-9)"
+ range 1 9 if X86_64
default "6" if X86_64
default "4" if X86_NUMAQ
default "3"
--
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