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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Andrew Morton , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Stanislav Fomichev , Jinjie Ruan , linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, linux-arch@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH v2 1/5] arch: select HAVE_ARCH_BITREVERSE conditionally on BITREVERSE Message-ID: References: <20260506175207.110893-1-ynorov@nvidia.com> <20260506175207.110893-2-ynorov@nvidia.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260506175207.110893-2-ynorov@nvidia.com> X-ClientProxiedBy: SJ0PR13CA0074.namprd13.prod.outlook.com (2603:10b6:a03:2c4::19) To CY8PR12MB8300.namprd12.prod.outlook.com (2603:10b6:930:7d::16) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CY8PR12MB8300:EE_|PH0PR12MB999090:EE_ X-MS-Office365-Filtering-Correlation-Id: 34efca56-1862-41d0-70d2-08deafcdb869 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|366016|1800799024|10070799003|56012099003|22082099003|18002099003|11063799003|921020|3023799003; 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On Wed, May 06, 2026 at 01:52:02PM -0400, Yury Norov wrote: > 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 > --- > 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