Hi Geert, On 3/2/23 10:47, Geert Uytterhoeven wrote:
Hi Alex, On Thu, Mar 2, 2023 at 10:35 AM Alexandre Ghiti <alexghiti@xxxxxxxxxxxx> 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. Changes since v3 <https://lore.kernel.org/all/20230214074925.228106-1-alexghiti@xxxxxxxxxxxx/>: * Added RB/AB * Added a mention to commit 622021cd6c56 ("s390: make command line configurable") in the cover letterThanks for the update! Apparently you forgot to add your own SoB?
I do not know, should I? Palmer did all the work, I only fixed 3 minor things
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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