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* [PATCH v3 0/3] arm64: Add two HWCAPs for Arm v8.7 FP behaviour
@ 2021-12-10 16:54 Joey Gouly
  2021-12-10 16:54 ` [PATCH v3 1/3] arm64: cpufeature: add HWCAP for FEAT_AFP Joey Gouly
                   ` (4 more replies)
  0 siblings, 5 replies; 6+ messages in thread
From: Joey Gouly @ 2021-12-10 16:54 UTC (permalink / raw)
  To: linux-arm-kernel
  Cc: nd, alexandru.elisei, catalin.marinas, corbet, james.morse,
	joey.gouly, maz, reijiw, suzuki.poulose, will

This series adds new HWCAPs for two Arm v8.7 features:
  - FEAT_AFP: Alternate floating-point behavior for specific
    floating point instructions.
  - FEAT_RPRES: Increased precision of Reciprocal Estimate and
    Reciprocal Square Root Estimate from an 8-bit mantissa to a
    12-bit mantissa.

These features can be enabled by userspace by setting some new bits
in FPCR. These new bits are FPCR.{NEP, AH, FIZ}. Since these must be
explicitly enabled by userspace, this should not affect existing
applications.

This has been tested with:
  - FVP: combinations of both features, including mismatched CPUs
  - qemu: regression test, neither feature is supported
  - juno: regression test, neither feature is supported

Changes since v2 [1]:
  - Add comment explaining the missing 0x1 value

Thanks,
Joey

[1] https://lore.kernel.org/linux-arm-kernel/20211207124226.50095-1-joey.gouly@arm.com/

Joey Gouly (3):
  arm64: cpufeature: add HWCAP for FEAT_AFP
  arm64: add ID_AA64ISAR2_EL1 sys register
  arm64: cpufeature: add HWCAP for FEAT_RPRES

 Documentation/arm64/cpu-feature-registers.rst | 17 +++++++++++++++++
 Documentation/arm64/elf_hwcaps.rst            |  8 ++++++++
 arch/arm64/include/asm/cpu.h                  |  1 +
 arch/arm64/include/asm/hwcap.h                |  2 ++
 arch/arm64/include/asm/sysreg.h               | 16 ++++++++++++++++
 arch/arm64/include/uapi/asm/hwcap.h           |  2 ++
 arch/arm64/kernel/cpufeature.c                | 13 +++++++++++++
 arch/arm64/kernel/cpuinfo.c                   |  3 +++
 arch/arm64/kvm/sys_regs.c                     |  2 +-
 9 files changed, 63 insertions(+), 1 deletion(-)

-- 
2.17.1


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^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2021-12-13 19:19 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2021-12-10 16:54 [PATCH v3 0/3] arm64: Add two HWCAPs for Arm v8.7 FP behaviour Joey Gouly
2021-12-10 16:54 ` [PATCH v3 1/3] arm64: cpufeature: add HWCAP for FEAT_AFP Joey Gouly
2021-12-10 16:54 ` [PATCH v3 2/3] arm64: add ID_AA64ISAR2_EL1 sys register Joey Gouly
2021-12-10 16:54 ` [PATCH v3 3/3] arm64: cpufeature: add HWCAP for FEAT_RPRES Joey Gouly
2021-12-10 17:31 ` [PATCH v3 0/3] arm64: Add two HWCAPs for Arm v8.7 FP behaviour Marc Zyngier
2021-12-13 19:17 ` Catalin Marinas

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