summaryrefslogtreecommitdiffstats
path: root/arch/s390/Kconfig
diff options
context:
space:
mode:
authorHeiko Carstens2013-09-18 11:45:36 +0200
committerMartin Schwidefsky2013-10-24 17:16:55 +0200
commit746479cdcbb131a0645e8cb4a35d6b26126e3e4c (patch)
tree7cf0fa041804197c14abe21c56bdf27c82274718 /arch/s390/Kconfig
parents390/s390dbf: use debug_level_enabled() where applicable (diff)
downloadkernel-qcow2-linux-746479cdcbb131a0645e8cb4a35d6b26126e3e4c.tar.gz
kernel-qcow2-linux-746479cdcbb131a0645e8cb4a35d6b26126e3e4c.tar.xz
kernel-qcow2-linux-746479cdcbb131a0645e8cb4a35d6b26126e3e4c.zip
s390/bitops: use generic find bit functions / reimplement _left variant
Just like all other architectures we should use out-of-line find bit operations, since the inline variant bloat the size of the kernel image. And also like all other architecures we should only supply optimized variants of the __ffs, ffs, etc. primitives. Therefore this patch removes the inlined s390 find bit functions and uses the generic out-of-line variants instead. The optimization of the primitives follows with the next patch. With this patch also the functions find_first_bit_left() and find_next_bit_left() have been reimplemented, since logically, they are nothing else but a find_first_bit()/find_next_bit() implementation that use an inverted __fls() instead of __ffs(). Also the restriction that these functions only work on machines which support the "flogr" instruction is gone now. This reduces the size of the kernel image (defconfig, -march=z9-109) by 144,482 bytes. Alone the size of the function build_sched_domains() gets reduced from 7 KB to 3,5 KB. We also git rid of unused functions like find_first_bit_le()... Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/Kconfig')
-rw-r--r--arch/s390/Kconfig1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 7143793859fa..a02177fb5ec1 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -99,6 +99,7 @@ config S390
select CLONE_BACKWARDS2
select GENERIC_CLOCKEVENTS
select GENERIC_CPU_DEVICES if !SMP
+ select GENERIC_FIND_FIRST_BIT
select GENERIC_SMP_IDLE_THREAD
select GENERIC_TIME_VSYSCALL_OLD
select HAVE_ALIGNED_STRUCT_PAGE if SLUB