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[80.39.24.67]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3bb676c9b1csm8361011f8f.45.2025.08.17.00.57.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 17 Aug 2025 00:57:41 -0700 (PDT) Message-ID: <4616546f-f10c-419b-a32f-ae1a059f15e4@gmail.com> Date: Sun, 17 Aug 2025 09:57:40 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Language: en-US, en-GB, es-ES From: Xose Vazquez Perez Subject: Re: [PATCH] LoongArch: Increase COMMAND_LINE_SIZE to 4096 To: Ming Wang Cc: LINUX_ARCH-ML , API-ML , KERNEL-ML , X86-ML Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Ming Wang wrote: > The default COMMAND_LINE_SIZE of 512, inherited from asm-generic, is > too small for modern use cases. For example, kdump configurations or > extensive debugging parameters can easily exceed this limit. > > Therefore, increase the command line size to 4096 bytes, aligning > LoongArch with the MIPS architecture. This change follows a broader > trend among architectures to raise this limit to support modern needs; > for instance, PowerPC increased its value for similar reasons in > commit a5980d064fe2 ("powerpc: Bump COMMAND_LINE_SIZE to 2048"). > > Similar to the change made for RISC-V in commit 61fc1ee8be26 > ("riscv: Bump COMMAND_LINE_SIZE value to 1024"), this is considered > a safe change. The broader kernel community has reached a consensus > that modifying COMMAND_LINE_SIZE from UAPI headers does not > constitute a uABI breakage, as well-behaved userspace applications > should not rely on this macro. > > Suggested-by: Huang Cun > Signed-off-by: Ming Wang > --- > arch/loongarch/include/uapi/asm/setup.h | 8 ++++++++ > 1 file changed, 8 insertions(+) > create mode 100644 arch/loongarch/include/uapi/asm/setup.h > > diff --git a/arch/loongarch/include/uapi/asm/setup.h b/arch/loongarch/include/uapi/asm/setup.h > new file mode 100644 > index 000000000000..d46363ce3e02 > --- /dev/null > +++ b/arch/loongarch/include/uapi/asm/setup.h > @@ -0,0 +1,8 @@ > +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ > + > +#ifndef _UAPI_ASM_LOONGARCH_SETUP_H > +#define _UAPI_ASM_LOONGARCH_SETUP_H > + > +#define COMMAND_LINE_SIZE 4096 > + > +#endif /* _UAPI_ASM_LOONGARCH_SETUP_H */ > -- > 2.43.0 A bit chaotic and arbitrary sizes: $ git grep "define.*COMMAND_LINE_SIZE" arch/alpha/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 256 arch/arc/include/asm/setup.h:#define COMMAND_LINE_SIZE 256 arch/arm64/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 2048 arch/arm/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 1024 arch/m68k/include/asm/setup.h:#define CL_SIZE COMMAND_LINE_SIZE arch/m68k/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 256 arch/microblaze/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 256 arch/mips/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 4096 arch/mips/loongson64/reset.c:#define KEXEC_ARGV_SIZE COMMAND_LINE_SIZE arch/parisc/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 1024 arch/powerpc/boot/ops.h:#define BOOT_COMMAND_LINE_SIZE 2048 arch/powerpc/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 2048 arch/riscv/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 1024 arch/s390/include/asm/setup.h:#define COMMAND_LINE_SIZE CONFIG_COMMAND_LINE_SIZE arch/s390/include/asm/setup.h:#define LEGACY_COMMAND_LINE_SIZE 896 arch/sparc/include/uapi/asm/setup.h:# define COMMAND_LINE_SIZE 2048 arch/sparc/include/uapi/asm/setup.h:# define COMMAND_LINE_SIZE 256 arch/um/include/asm/setup.h:#define COMMAND_LINE_SIZE 4096 arch/x86/include/asm/setup.h:#define COMMAND_LINE_SIZE 2048 arch/xtensa/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 256 include/uapi/asm-generic/setup.h:#define COMMAND_LINE_SIZE 512 kernel/trace/ftrace.c:#define FTRACE_FILTER_SIZE COMMAND_LINE_SIZE tools/power/x86/turbostat/turbostat.c:#define COMMAND_LINE_SIZE 2048 tools/testing/selftests/kho/init.c:#define COMMAND_LINE_SIZE 2048 Maybe they should be standardized ??? And for s390 it is configurable, see 622021cd6c560