From 3fd97cf3234c5ffbd420319d1d510e4940183843 Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Wed, 24 Jan 2024 18:12:37 +0000 Subject: [PATCH] arm64/fp: Clarify effect of setting an unsupported system VL 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 Signed-off-by: Mark Brown Reviewed-by: Dave Martin Link: https://lore.kernel.org/r/20240124-arm64-sve-sme-doc-v2-3-fe3964fb3c19@kernel.org Signed-off-by: Catalin Marinas --- 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..f4376c06f447 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 PR_SME_SET_VL. 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..8d8837fc39ec 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 PR_SVE_SET_VL. The result can be determined by reopening the file and reading its contents.