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Date: Fri, 9 Feb 2018 14:01:50 -0800
From: Randy Dunlap <rdunlap@...radead.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>,
X86 ML <x86@...nel.org>
Cc: LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86: try to simplify NR_CPUS config
From: Randy Dunlap <rdunlap@...radead.org>
Clean up and simplify the X86 NR_CPUS Kconfig symbol/option by
introducing MIN_CONFIG_CPUS, MAX_CONFIG_CPUS, and DEF_CONFIG_CPUS.
Then combine some default values when their conditionals can be
reduced.
Also move the X86_BIGSMP kconfig option inside an "if X86_32"/"endif"
config block and drop its explicit "depends on X86_32".
This is a rather literal interpretation of Linus's suggestion.
It mostly moves the complexity to other kconfig symbols, although
a little bit more reduction can be done, especially in
RANGE_BEGIN_CPUS, at the sake of understandability, so I chose
to leave it more understandable (at least to me).
Suggested-by: Linus Torvalds <torvalds@...uxfoundation.org>
Link: lkml.kernel.org/r/CA+55aFzOd3j6ZUSkEwTdk85qtt1JywOtm3ZAb-qAvt8_hJ6D4A@...l.gmail.com
Signed-off-by: Randy Dunlap <rdunlap@...radead.org>
Cc: x86@...nel.org
---
arch/x86/Kconfig | 48 ++++++++++++++++++++++++++++++---------------
1 file changed, 33 insertions(+), 15 deletions(-)
--- linux-next-20180209.orig/arch/x86/Kconfig
+++ linux-next-20180209/arch/x86/Kconfig
@@ -423,12 +423,6 @@ config X86_MPPARSE
For old smp systems that do not have proper acpi support. Newer systems
(esp with 64bit cpus) with acpi support, MADT and DSDT will override it
-config X86_BIGSMP
- bool "Support for big SMP systems with more than 8 CPUs"
- depends on X86_32 && SMP
- ---help---
- This option is needed for the systems that have more than 8 CPUs
-
config GOLDFISH
def_bool y
depends on X86_GOLDFISH
@@ -460,6 +454,12 @@ config INTEL_RDT
Say N if unsure.
if X86_32
+config X86_BIGSMP
+ bool "Support for big SMP systems with more than 8 CPUs"
+ depends on SMP
+ ---help---
+ This option is needed for the systems that have more than 8 CPUs
+
config X86_EXTENDED_PLATFORM
bool "Support for extended (non-PC) x86 platforms"
default y
@@ -949,17 +949,35 @@ config MAXSMP
Enable maximum number of CPUS and NUMA Nodes for this architecture.
If unsure, say N.
+config RANGE_BEGIN_CPUS
+ int
+ default 2 if SMP && X86_32
+ default 2 if SMP && !MAXSMP && X86_64
+ default 8192 if SMP && MAXSMP && X86_64
+ default 1 if !SMP
+ default 2
+
+config RANGE_END_CPUS
+ int
+ default 8 if SMP && X86_32 && !X86_BIGSMP
+ default 64 if SMP && X86_32 && X86_BIGSMP
+ default 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK && X86_64
+ default 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
+ default 8192 if SMP && MAXSMP && X86_64
+ default 1 if !SMP
+
+config DEF_CONFIG_CPUS
+ int
+ default 1 if !SMP
+ default 8192 if MAXSMP
+ default 32 if SMP && X86_BIGSMP
+ default 8 if SMP && X86_32
+ default 64 if SMP
+
config NR_CPUS
int "Maximum number of CPUs" if SMP && !MAXSMP
- range 2 8 if SMP && X86_32 && !X86_BIGSMP
- range 2 64 if SMP && X86_32 && X86_BIGSMP
- range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK && X86_64
- range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
- default "1" if !SMP
- default "8192" if MAXSMP
- default "32" if SMP && X86_BIGSMP
- default "8" if SMP && X86_32
- default "64" if SMP
+ range RANGE_BEGIN_CPUS RANGE_END_CPUS
+ default DEF_CONFIG_CPUS
---help---
This allows you to specify the maximum number of CPUs which this
kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
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