Re: [PATCH 3/4] arm64/fp: Clarify effect of setting an unsupported system VL
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From: Dave Martin <Dave.Martin@arm.com>
Date: 2024-01-23 15:49:30
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On Mon, Jan 22, 2024 at 08:41:53PM +0000, Mark Brown wrote:
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The documentation for system vector length configuration does not cover all cases where unsupported values are written, tighten it up. Reported-by: Edmund Grimley-Evans <redacted> Signed-off-by: Mark Brown <broonie@kernel.org> --- Documentation/arch/arm64/sme.rst | 5 ++--- Documentation/arch/arm64/sve.rst | 5 ++--- 2 files changed, 4 insertions(+), 6 deletions(-)diff --git a/Documentation/arch/arm64/sme.rst b/Documentation/arch/arm64/sme.rst index 3133d0e91b48..ba0a5e5b2523 100644 --- a/Documentation/arch/arm64/sme.rst +++ b/Documentation/arch/arm64/sme.rst@@ -379,9 +379,8 @@ The regset data starts with struct user_za_header, containing: /proc/sys/abi/sme_default_vector_length Writing the text representation of an integer to this file sets the system - default vector length to the specified value, unless the value is greater - than the maximum vector length supported by the system in which case the - default vector length is set to that maximum. + default vector length to the specified value rounded to a supported value + using the same rules as for setting vector length via prctl().
Do parallel changes need to be made in sve.rst? (There seems to be so much duplication and copy-paste between these files that I wonder whether it would make sense to merge them... but that's probably a separate discussion.) Nit: is it better to name the prctl here than just to say prctl()? That would be easier for the reader to cross-reference.
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The result can be determined by reopening the file and reading its contents.diff --git a/Documentation/arch/arm64/sve.rst b/Documentation/arch/arm64/sve.rst index b45a2da19bf1..b923727ff4b9 100644 --- a/Documentation/arch/arm64/sve.rst +++ b/Documentation/arch/arm64/sve.rst@@ -423,9 +423,8 @@ The regset data starts with struct user_sve_header, containing: /proc/sys/abi/sve_default_vector_length Writing the text representation of an integer to this file sets the system - default vector length to the specified value, unless the value is greater - than the maximum vector length supported by the system in which case the - default vector length is set to that maximum. + default vector length to the specified value rounded to a supported value + using the same rules as for setting vector length via prctl().
Ditto. [...] Cheers ---Dave _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel