From: "Philippe Mathieu-Daudé" <philmd@linaro.org>
To: Alexandre Ghiti <alexghiti@rivosinc.com>,
Greg KH <gregkh@linuxfoundation.org>,
Jonathan Corbet <corbet@lwn.net>,
Richard Henderson <richard.henderson@linaro.org>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Matt Turner <mattst88@gmail.com>,
Vineet Gupta <vgupta@kernel.org>,
Russell King <linux@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Huacai Chen <chenhuacai@kernel.org>,
WANG Xuerui <kernel@xen0n.name>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Michal Simek <monstr@monstr.eu>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
"James E . J . Bottomley" <James.Bottomley@HansenPartnership.com>,
Helge Deller <deller@gmx.de>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.co>
Subject: Re: [PATCH v5 00/26] Remove COMMAND_LINE_SIZE from uapi
Date: Mon, 6 Mar 2023 14:19:15 +0100 [thread overview]
Message-ID: <e1fa23ff-951e-176b-1a84-cbaab34ed44d__22789.9248989829$1678108776$gmane$org@linaro.org> (raw)
In-Reply-To: <20230306100508.1171812-1-alexghiti@rivosinc.com>
On 6/3/23 11:04, Alexandre Ghiti wrote:
> This all came up in the context of increasing COMMAND_LINE_SIZE in the
> RISC-V port. In theory that's a UABI break, as COMMAND_LINE_SIZE is the
> maximum length of /proc/cmdline and userspace could staticly rely on
> that to be correct.
>
> Usually I wouldn't mess around with changing this sort of thing, but
> PowerPC increased it with a5980d064fe2 ("powerpc: Bump COMMAND_LINE_SIZE
> to 2048"). There are also a handful of examples of COMMAND_LINE_SIZE
> increasing, but they're from before the UAPI split so I'm not quite sure
> what that means: e5a6a1c90948 ("powerpc: derive COMMAND_LINE_SIZE from
> asm-generic"), 684d2fd48e71 ("[S390] kernel: Append scpdata to kernel
> boot command line"), 22242681cff5 ("MIPS: Extend COMMAND_LINE_SIZE"),
> and 2b74b85693c7 ("sh: Derive COMMAND_LINE_SIZE from
> asm-generic/setup.h.").
>
> It seems to me like COMMAND_LINE_SIZE really just shouldn't have been
> part of the uapi to begin with, and userspace should be able to handle
> /proc/cmdline of whatever length it turns out to be. I don't see any
> references to COMMAND_LINE_SIZE anywhere but Linux via a quick Google
> search, but that's not really enough to consider it unused on my end.
>
> This issue was already considered in s390 and they reached the same
> conclusion in commit 622021cd6c56 ("s390: make command line
> configurable").
>
> The feedback on the v1 seemed to indicate that COMMAND_LINE_SIZE really
> shouldn't be part of uapi, so this now touches all the ports. I've
> tried to split this all out and leave it bisectable, but I haven't
> tested it all that aggressively.
Series:
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
next prev parent reply other threads:[~2023-03-06 13:19 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230306100508.1171812-1-alexghiti@rivosinc.com>
2023-03-06 10:04 ` [PATCH v5 01/26] alpha: Remove COMMAND_LINE_SIZE from uapi Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 02/26] arm64: " Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 03/26] arm: " Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 04/26] ia64: " Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 05/26] m68k: " Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 06/26] microblaze: " Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 07/26] mips: " Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 08/26] parisc: " Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 09/26] powerpc: " Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 10/26] sparc: " Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 11/26] xtensa: " Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 12/26] riscv: " Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 13/26] asm-generic: " Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 14/26] alpha: Remove empty <uapi/asm/setup.h> Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 15/26] arc: " Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 16/26] m68k: " Alexandre Ghiti
2023-03-06 10:04 ` [PATCH v5 17/26] arm64: " Alexandre Ghiti
2023-03-06 10:05 ` [PATCH v5 18/26] microblaze: " Alexandre Ghiti
2023-03-06 10:05 ` [PATCH v5 19/26] sparc: " Alexandre Ghiti
2023-03-06 10:05 ` [PATCH v5 20/26] parisc: " Alexandre Ghiti
2023-03-06 10:05 ` [PATCH v5 21/26] x86: " Alexandre Ghiti
2023-03-06 10:05 ` [PATCH v5 22/26] xtensa: " Alexandre Ghiti
2023-03-06 10:05 ` [PATCH v5 23/26] powerpc: " Alexandre Ghiti
2023-03-06 10:05 ` [PATCH v5 24/26] mips: " Alexandre Ghiti
2023-03-06 10:05 ` [PATCH v5 25/26] s390: " Alexandre Ghiti
2023-03-06 10:05 ` [PATCH v5 26/26] riscv: " Alexandre Ghiti
2023-03-06 13:19 ` Philippe Mathieu-Daudé [this message]
2023-05-09 7:06 ` [PATCH v5 00/26] Remove COMMAND_LINE_SIZE from uapi Alexandre Ghiti
[not found] ` <20230306100508.1171812-15-alexghiti@rivosinc.com>
2023-05-16 0:53 ` [PATCH v5 14/26] alpha: Remove empty <uapi/asm/setup.h> Maciej W. Rozycki
2023-03-06 10:04 [PATCH v5 00/26] Remove COMMAND_LINE_SIZE from uapi Alexandre Ghiti
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