[PATCH 2/2] x86: Modify Kconfig to allow up to 4096 cpus

From: Mike Travis
Date: Tue Mar 25 2008 - 21:43:32 EST


Increase the limit of NR_CPUS to 4096 and introduce a boolean
called "MAXSMP" which when set (e.g. "allyesconfig"), will set
NR_CPUS = 4096 and NODES_SHIFT = 9 (512).

Based on:
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86.git

Signed-off-by: Mike Travis <travis@xxxxxxx>
---
arch/x86/Kconfig | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)

--- linux.trees.git.orig/arch/x86/Kconfig
+++ linux.trees.git/arch/x86/Kconfig
@@ -522,16 +522,24 @@ config SWIOTLB
access 32-bits of memory can be used on systems with more than
3 GB of memory. If unsure, say Y.

+config MAXSMP
+ bool "Configure Maximum number of SMP Processors"
+ depends on X86_64 && SMP
+ default n
+ help
+ Configure maximum number of CPUS for this architecture.
+ If unsure, say N.

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 "4096" if MAXSMP
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
@@ -918,12 +926,16 @@ config NUMA_EMU
number of nodes. This is only useful for debugging.

config NODES_SHIFT
- int "Max num nodes shift(1-15)"
+ int "Maximum NUMA Nodes (as a power of 2)"
range 1 15 if X86_64
+ default "9" if MAXSMP
default "6" if X86_64
default "4" if X86_NUMAQ
default "3"
depends on NEED_MULTIPLE_NODES
+ help
+ Specify the maximum number of NUMA Nodes available on the target
+ system. Increases memory reserved to accomodate various tables.

config HAVE_ARCH_BOOTMEM_NODE
def_bool y

--
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