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| author | Joey Gouly <joey.gouly@arm.com> | 2021-12-10 16:54:32 +0000 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2021-12-13 18:53:00 +0000 |
| commit | 1175011a7d0030d49dc9c10bde36f08f26d0a8ee (patch) | |
| tree | d4ec5130ec2454c6e8137c1cb2bab1a04f26d01c /Documentation/arm64/cpu-feature-registers.rst | |
| parent | 9e45365f1469ef2b934f9d035975dbc9ad352116 (diff) | |
| download | lwn-1175011a7d0030d49dc9c10bde36f08f26d0a8ee.tar.gz lwn-1175011a7d0030d49dc9c10bde36f08f26d0a8ee.zip | |
arm64: cpufeature: add HWCAP for FEAT_RPRES
Add a new HWCAP to detect the Increased precision of Reciprocal Estimate
and Reciprocal Square Root Estimate feature (FEAT_RPRES), introduced in Armv8.7.
Also expose this to userspace in the ID_AA64ISAR2_EL1 feature register.
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211210165432.8106-4-joey.gouly@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'Documentation/arm64/cpu-feature-registers.rst')
| -rw-r--r-- | Documentation/arm64/cpu-feature-registers.rst | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/Documentation/arm64/cpu-feature-registers.rst b/Documentation/arm64/cpu-feature-registers.rst index 1b19d20c2dbd..749ae970c319 100644 --- a/Documentation/arm64/cpu-feature-registers.rst +++ b/Documentation/arm64/cpu-feature-registers.rst @@ -283,6 +283,14 @@ infrastructure: | AFP | [47-44] | y | +------------------------------+---------+---------+ + 9) ID_AA64ISAR2_EL1 - Instruction set attribute register 2 + + +------------------------------+---------+---------+ + | Name | bits | visible | + +------------------------------+---------+---------+ + | RPRES | [7-4] | y | + +------------------------------+---------+---------+ + Appendix I: Example ------------------- |