The patch titled
Subject: cpumask: limit visibility of FORCE_NR_CPUS
has been added to the -mm mm-nonmm-unstable branch. Its filename is
cpumask-limit-visibility-of-force_nr_cpus.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/cpumask-limit-visibility-of-force_nr_cpus.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Yury Norov <yury.norov@xxxxxxxxx>
Subject: cpumask: limit visibility of FORCE_NR_CPUS
Date: Wed, 19 Oct 2022 15:59:39 -0700
In current form, FORCE_NR_CPUS is visible to all users building their
kernels, even not experts. It is also set in allmodconfig or
allyesconfig, which is not a correct behavior.
The 'choice' and unused config UNFORCE_NR_CPUS are used to ensure that
auto-generated configs that try to enable as much options as possible,
like allmodconfig, don't enable FORCE_NR_CPUS.
Link: https://lkml.kernel.org/r/20221019225939.1646349-1-yury.norov@xxxxxxxxx
Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>
Suggested-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Alexey Klimov <klimov.linux@xxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Eric Biggers <ebiggers@xxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Cc: Sander Vanheule <sander@xxxxxxxxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Valentin Schneider <vschneid@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/Kconfig | 31 ++++++++++++++++++++++++-------
1 file changed, 24 insertions(+), 7 deletions(-)
--- a/lib/Kconfig~cpumask-limit-visibility-of-force_nr_cpus
+++ a/lib/Kconfig
@@ -528,14 +528,31 @@ config CPUMASK_OFFSTACK
them on the stack. This is a bit more expensive, but avoids
stack overflow.
+choice
+ prompt "Number of CPUs detection method"
+ default UNFORCE_NR_CPUS
+ depends on SMP && EXPERT
+ help
+ Select between boot-time and compile-time detection of number
+ of CPUs. If it's possible to provide exact number of CPUs at
+ compile-time, kernel code may be optimized better.
+ For general-purpose kernel, choose "boot time" option.
+
+config UNFORCE_NR_CPUS
+ bool "Set number of CPUs at boot time"
+ help
+ Choose it if you build general-purpose kernel and want to rely
+ on kernel to detect actual number of CPUs.
+
config FORCE_NR_CPUS
- bool "NR_CPUS is set to an actual number of CPUs"
- depends on SMP
- help
- Say Yes if you have NR_CPUS set to an actual number of possible
- CPUs in your system, not to a default value. This forces the core
- code to rely on compile-time value and optimize kernel routines
- better.
+ bool "Set number of CPUs at compile time"
+ help
+ Choose it if NR_CPUS corresponds to an actual number of
+ possible CPUs in your system. This forces the core code
+ to rely on compile-time value and optimize kernel routines
+ better.
+
+endchoice
config CPU_RMAP
bool
_
Patches currently in -mm which might be from yury.norov@xxxxxxxxx are
cpumask-limit-visibility-of-force_nr_cpus.patch
