diff options
Diffstat (limited to 'Documentation/arch/arm64')
| -rw-r--r-- | Documentation/arch/arm64/elf_hwcaps.rst | 49 | ||||
| -rw-r--r-- | Documentation/arch/arm64/silicon-errata.rst | 5 | ||||
| -rw-r--r-- | Documentation/arch/arm64/sme.rst | 11 | ||||
| -rw-r--r-- | Documentation/arch/arm64/sve.rst | 10 |
4 files changed, 59 insertions, 16 deletions
diff --git a/Documentation/arch/arm64/elf_hwcaps.rst b/Documentation/arch/arm64/elf_hwcaps.rst index ced7b335e..448c16648 100644 --- a/Documentation/arch/arm64/elf_hwcaps.rst +++ b/Documentation/arch/arm64/elf_hwcaps.rst @@ -317,6 +317,55 @@ HWCAP2_LRCPC3 HWCAP2_LSE128 Functionality implied by ID_AA64ISAR0_EL1.Atomic == 0b0011. +HWCAP2_FPMR + Functionality implied by ID_AA64PFR2_EL1.FMR == 0b0001. + +HWCAP2_LUT + Functionality implied by ID_AA64ISAR2_EL1.LUT == 0b0001. + +HWCAP2_FAMINMAX + Functionality implied by ID_AA64ISAR3_EL1.FAMINMAX == 0b0001. + +HWCAP2_F8CVT + Functionality implied by ID_AA64FPFR0_EL1.F8CVT == 0b1. + +HWCAP2_F8FMA + Functionality implied by ID_AA64FPFR0_EL1.F8FMA == 0b1. + +HWCAP2_F8DP4 + Functionality implied by ID_AA64FPFR0_EL1.F8DP4 == 0b1. + +HWCAP2_F8DP2 + Functionality implied by ID_AA64FPFR0_EL1.F8DP2 == 0b1. + +HWCAP2_F8E4M3 + Functionality implied by ID_AA64FPFR0_EL1.F8E4M3 == 0b1. + +HWCAP2_F8E5M2 + Functionality implied by ID_AA64FPFR0_EL1.F8E5M2 == 0b1. + +HWCAP2_SME_LUTV2 + Functionality implied by ID_AA64SMFR0_EL1.LUTv2 == 0b1. + +HWCAP2_SME_F8F16 + Functionality implied by ID_AA64SMFR0_EL1.F8F16 == 0b1. + +HWCAP2_SME_F8F32 + Functionality implied by ID_AA64SMFR0_EL1.F8F32 == 0b1. + +HWCAP2_SME_SF8FMA + Functionality implied by ID_AA64SMFR0_EL1.SF8FMA == 0b1. + +HWCAP2_SME_SF8DP4 + Functionality implied by ID_AA64SMFR0_EL1.SF8DP4 == 0b1. + +HWCAP2_SME_SF8DP2 + Functionality implied by ID_AA64SMFR0_EL1.SF8DP2 == 0b1. + +HWCAP2_SME_SF8DP4 + Functionality implied by ID_AA64SMFR0_EL1.SF8DP4 == 0b1. + + 4. Unused AT_HWCAP bits ----------------------- diff --git a/Documentation/arch/arm64/silicon-errata.rst b/Documentation/arch/arm64/silicon-errata.rst index 45a7f4932..d33e27c5c 100644 --- a/Documentation/arch/arm64/silicon-errata.rst +++ b/Documentation/arch/arm64/silicon-errata.rst @@ -35,8 +35,9 @@ can be triggered by Linux). For software workarounds that may adversely impact systems unaffected by the erratum in question, a Kconfig entry is added under "Kernel Features" -> "ARM errata workarounds via the alternatives framework". -These are enabled by default and patched in at runtime when an affected -CPU is detected. For less-intrusive workarounds, a Kconfig option is not +With the exception of workarounds for errata deemed "rare" by Arm, these +are enabled by default and patched in at runtime when an affected CPU is +detected. For less-intrusive workarounds, a Kconfig option is not available and the code is structured (preferably with a comment) in such a way that the erratum will not be hit. diff --git a/Documentation/arch/arm64/sme.rst b/Documentation/arch/arm64/sme.rst index 3d0e53eca..be317d457 100644 --- a/Documentation/arch/arm64/sme.rst +++ b/Documentation/arch/arm64/sme.rst @@ -75,7 +75,7 @@ model features for SME is included in Appendix A. 2. Vector lengths ------------------ -SME defines a second vector length similar to the SVE vector length which is +SME defines a second vector length similar to the SVE vector length which controls the size of the streaming mode SVE vectors and the ZA matrix array. The ZA matrix is square with each side having as many bytes as a streaming mode SVE vector. @@ -238,12 +238,12 @@ prctl(PR_SME_SET_VL, unsigned long arg) bits of Z0..Z31 except for Z0 bits [127:0] .. Z31 bits [127:0] to become unspecified, including both streaming and non-streaming SVE state. Calling PR_SME_SET_VL with vl equal to the thread's current vector - length, or calling PR_SME_SET_VL with the PR_SVE_SET_VL_ONEXEC flag, + length, or calling PR_SME_SET_VL with the PR_SME_SET_VL_ONEXEC flag, does not constitute a change to the vector length for this purpose. * Changing the vector length causes PSTATE.ZA and PSTATE.SM to be cleared. Calling PR_SME_SET_VL with vl equal to the thread's current vector - length, or calling PR_SME_SET_VL with the PR_SVE_SET_VL_ONEXEC flag, + length, or calling PR_SME_SET_VL with the PR_SME_SET_VL_ONEXEC flag, does not constitute a change to the vector length for this purpose. @@ -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 0d9a426e9..8d8837fc3 100644 --- a/Documentation/arch/arm64/sve.rst +++ b/Documentation/arch/arm64/sve.rst @@ -117,11 +117,6 @@ the SVE instruction set architecture. * The SVE registers are not used to pass arguments to or receive results from any syscall. -* In practice the affected registers/bits will be preserved or will be replaced - with zeros on return from a syscall, but userspace should not make - assumptions about this. The kernel behaviour may vary on a case-by-case - basis. - * All other SVE state of a thread, including the currently configured vector length, the state of the PR_SVE_VL_INHERIT flag, and the deferred vector length (if any), is preserved across all syscalls, subject to the specific @@ -428,9 +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. |