From: Yury Norov <ynorov@nvidia.com>
To: Paul Walmsley <pjw@kernel.org>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Alexandre Ghiti <alex@ghiti.fr>,
Yury Norov <yury.norov@gmail.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Arnd Bergmann <arnd@arndb.de>, Eric Biggers <ebiggers@kernel.org>,
Andrew Lunn <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Jesper Dangaard Brouer <hawk@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
Stanislav Fomichev <sdf@fomichev.me>,
Jinjie Ruan <ruanjinjie@huawei.com>,
linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org,
linux-arch@vger.kernel.org, netdev@vger.kernel.org,
bpf@vger.kernel.org
Cc: Yury Norov <ynorov@nvidia.com>
Subject: [PATCH v2 1/5] arch: select HAVE_ARCH_BITREVERSE conditionally on BITREVERSE
Date: Wed, 6 May 2026 13:52:02 -0400 [thread overview]
Message-ID: <20260506175207.110893-2-ynorov@nvidia.com> (raw)
In-Reply-To: <20260506175207.110893-1-ynorov@nvidia.com>
Architectures may have bit reversal instructions, but if the API not
needed, the corresponding option should not be selected because it may
lead to generating the unneeded code.
Signed-off-by: Yury Norov <ynorov@nvidia.com>
---
arch/arm/Kconfig | 2 +-
arch/arm64/Kconfig | 2 +-
arch/loongarch/Kconfig | 2 +-
arch/mips/Kconfig | 2 +-
lib/Kconfig | 1 +
5 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 71fc5dd4123f..0e963e54fe06 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -83,7 +83,7 @@ config ARM
select HARDIRQS_SW_RESEND
select HAS_IOPORT
select HAVE_ARCH_AUDITSYSCALL if AEABI && !OABI_COMPAT
- select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
+ select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6 && BITREVERSE
select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU && (!PREEMPT_RT || !SMP)
select HAVE_ARCH_KFENCE if MMU && !XIP_KERNEL
select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index fe60738e5943..f5bb62c2ba9c 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -150,7 +150,7 @@ config ARM64
select HAVE_ACPI_APEI if (ACPI && EFI)
select HAVE_ALIGNED_STRUCT_PAGE
select HAVE_ARCH_AUDITSYSCALL
- select HAVE_ARCH_BITREVERSE
+ select HAVE_ARCH_BITREVERSE if BITREVERSE
select HAVE_ARCH_COMPILER_H
select HAVE_ARCH_HUGE_VMALLOC
select HAVE_ARCH_HUGE_VMAP
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 3b042dbb2c41..6c3444e31c0e 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -115,7 +115,7 @@ config LOONGARCH
select HAS_IOPORT
select HAVE_ALIGNED_STRUCT_PAGE if 64BIT
select HAVE_ARCH_AUDITSYSCALL
- select HAVE_ARCH_BITREVERSE if 64BIT
+ select HAVE_ARCH_BITREVERSE if 64BIT && BITREVERSE
select HAVE_ARCH_JUMP_LABEL
select HAVE_ARCH_JUMP_LABEL_RELATIVE
select HAVE_ARCH_KASAN if 64BIT
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 4364f3dba688..7e1494e0dbfa 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2026,7 +2026,7 @@ config CPU_MIPSR6
default y if CPU_MIPS32_R6 || CPU_MIPS64_R6
select CPU_HAS_RIXI
select CPU_HAS_DIEI if !CPU_DIEI_BROKEN
- select HAVE_ARCH_BITREVERSE
+ select HAVE_ARCH_BITREVERSE if BITREVERSE
select MIPS_ASID_BITS_VARIABLE
select MIPS_SPRAM
diff --git a/lib/Kconfig b/lib/Kconfig
index 00a9509636c1..d8e7e89ae320 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -58,6 +58,7 @@ config BITREVERSE
config HAVE_ARCH_BITREVERSE
bool
default n
+ depends on BITREVERSE
help
This option enables the use of hardware bit-reversal instructions on
architectures which support such operations.
--
2.51.0
next prev parent reply other threads:[~2026-05-06 17:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-06 17:52 Yury Norov
2026-05-06 17:52 ` Yury Norov [this message]
2026-05-06 17:52 ` [PATCH v2 2/5] lib/bitrev: Introduce GENERIC_BITREVERSE Yury Norov
2026-05-06 17:52 ` [PATCH v2 3/5] bitops: Define generic___bitrev8/16/32 for reuse Yury Norov
2026-05-06 17:52 ` [PATCH v2 4/5] arch/riscv: Add bitrev.h file to support rev8 and brev8 Yury Norov
2026-05-06 17:52 ` [PATCH v2 5/5] MAINTAINERS: BITOPS: include bitrev.[ch] Yury Norov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260506175207.110893-2-ynorov@nvidia.com \
--to=ynorov@nvidia.com \
--cc=akpm@linux-foundation.org \
--cc=alex@ghiti.fr \
--cc=andrew+netdev@lunn.ch \
--cc=aou@eecs.berkeley.edu \
--cc=arnd@arndb.de \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=davem@davemloft.net \
--cc=ebiggers@kernel.org \
--cc=edumazet@google.com \
--cc=hawk@kernel.org \
--cc=john.fastabend@gmail.com \
--cc=kuba@kernel.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=linux@rasmusvillemoes.dk \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=palmer@dabbelt.com \
--cc=pjw@kernel.org \
--cc=ruanjinjie@huawei.com \
--cc=sdf@fomichev.me \
--cc=yury.norov@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox