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Message-ID: <CADnq5_Pub0UULb6UqO2g+Eo6RCy=gqtWLN9txjEyp2Gmw9idww@mail.gmail.com>
Date: Wed, 3 Jan 2024 09:27:47 -0500
From: Alex Deucher <alexdeucher@...il.com>
To: Samuel Holland <samuel.holland@...ive.com>
Cc: linux-arm-kernel@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org,
x86@...nel.org, linux-riscv@...ts.infradead.org,
Christoph Hellwig <hch@....de>, linux-arch@...r.kernel.org, Jonathan Corbet <corbet@....net>,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
amd-gfx@...ts.freedesktop.org, loongarch@...ts.linux.dev
Subject: Re: [PATCH v2 00/14] Unified cross-architecture kernel-mode FPU API
On Thu, Dec 28, 2023 at 5:11 AM Samuel Holland
<samuel.holland@...ive.com> wrote:
>
> This series unifies the kernel-mode FPU API across several architectures
> by wrapping the existing functions (where needed) in consistently-named
> functions placed in a consistent header location, with mostly the same
> semantics: they can be called from preemptible or non-preemptible task
> context, and are not assumed to be reentrant. Architectures are also
> expected to provide CFLAGS adjustments for compiling FPU-dependent code.
> For the moment, SIMD/vector units are out of scope for this common API.
>
> This allows us to remove the ifdeffery and duplicated Makefile logic at
> each FPU user. It then implements the common API on RISC-V, and converts
> a couple of users to the new API: the AMDGPU DRM driver, and the FPU
> self test.
>
> The underlying goal of this series is to allow using newer AMD GPUs
> (e.g. Navi) on RISC-V boards such as SiFive's HiFive Unmatched. Those
> GPUs need CONFIG_DRM_AMD_DC_FP to initialize, which requires kernel-mode
> FPU support.
Series is:
Acked-by: Alex Deucher <alexander.deucher@....com>
>
> Previous versions:
> v1: https://lore.kernel.org/linux-kernel/20231208055501.2916202-1-samuel.holland@sifive.com/
> v0: https://lore.kernel.org/linux-kernel/20231122030621.3759313-1-samuel.holland@sifive.com/
>
> Changes in v2:
> - Add documentation explaining the built-time and runtime APIs
> - Add a linux/fpu.h header for generic isolation enforcement
> - Remove file name from header comment
> - Clean up arch/arm64/lib/Makefile, like for arch/arm
> - Remove RISC-V architecture-specific preprocessor check
> - Split altivec removal to a separate patch
> - Use linux/fpu.h instead of asm/fpu.h in consumers
> - Declare test_fpu() in a header
>
> Michael Ellerman (1):
> drm/amd/display: Only use hard-float, not altivec on powerpc
>
> Samuel Holland (13):
> arch: Add ARCH_HAS_KERNEL_FPU_SUPPORT
> ARM: Implement ARCH_HAS_KERNEL_FPU_SUPPORT
> ARM: crypto: Use CC_FLAGS_FPU for NEON CFLAGS
> arm64: Implement ARCH_HAS_KERNEL_FPU_SUPPORT
> arm64: crypto: Use CC_FLAGS_FPU for NEON CFLAGS
> lib/raid6: Use CC_FLAGS_FPU for NEON CFLAGS
> LoongArch: Implement ARCH_HAS_KERNEL_FPU_SUPPORT
> powerpc: Implement ARCH_HAS_KERNEL_FPU_SUPPORT
> x86: Implement ARCH_HAS_KERNEL_FPU_SUPPORT
> riscv: Add support for kernel-mode FPU
> drm/amd/display: Use ARCH_HAS_KERNEL_FPU_SUPPORT
> selftests/fpu: Move FP code to a separate translation unit
> selftests/fpu: Allow building on other architectures
>
> Documentation/core-api/floating-point.rst | 78 +++++++++++++++++++
> Documentation/core-api/index.rst | 1 +
> Makefile | 5 ++
> arch/Kconfig | 6 ++
> arch/arm/Kconfig | 1 +
> arch/arm/Makefile | 7 ++
> arch/arm/include/asm/fpu.h | 15 ++++
> arch/arm/lib/Makefile | 3 +-
> arch/arm64/Kconfig | 1 +
> arch/arm64/Makefile | 9 ++-
> arch/arm64/include/asm/fpu.h | 15 ++++
> arch/arm64/lib/Makefile | 6 +-
> arch/loongarch/Kconfig | 1 +
> arch/loongarch/Makefile | 5 +-
> arch/loongarch/include/asm/fpu.h | 1 +
> arch/powerpc/Kconfig | 1 +
> arch/powerpc/Makefile | 5 +-
> arch/powerpc/include/asm/fpu.h | 28 +++++++
> arch/riscv/Kconfig | 1 +
> arch/riscv/Makefile | 3 +
> arch/riscv/include/asm/fpu.h | 16 ++++
> arch/riscv/kernel/Makefile | 1 +
> arch/riscv/kernel/kernel_mode_fpu.c | 28 +++++++
> arch/x86/Kconfig | 1 +
> arch/x86/Makefile | 20 +++++
> arch/x86/include/asm/fpu.h | 13 ++++
> drivers/gpu/drm/amd/display/Kconfig | 2 +-
> .../gpu/drm/amd/display/amdgpu_dm/dc_fpu.c | 35 +--------
> drivers/gpu/drm/amd/display/dc/dml/Makefile | 36 +--------
> drivers/gpu/drm/amd/display/dc/dml2/Makefile | 36 +--------
> include/linux/fpu.h | 12 +++
> lib/Kconfig.debug | 2 +-
> lib/Makefile | 26 +------
> lib/raid6/Makefile | 31 ++------
> lib/test_fpu.h | 8 ++
> lib/{test_fpu.c => test_fpu_glue.c} | 37 ++-------
> lib/test_fpu_impl.c | 37 +++++++++
> 37 files changed, 343 insertions(+), 190 deletions(-)
> create mode 100644 Documentation/core-api/floating-point.rst
> create mode 100644 arch/arm/include/asm/fpu.h
> create mode 100644 arch/arm64/include/asm/fpu.h
> create mode 100644 arch/powerpc/include/asm/fpu.h
> create mode 100644 arch/riscv/include/asm/fpu.h
> create mode 100644 arch/riscv/kernel/kernel_mode_fpu.c
> create mode 100644 arch/x86/include/asm/fpu.h
> create mode 100644 include/linux/fpu.h
> create mode 100644 lib/test_fpu.h
> rename lib/{test_fpu.c => test_fpu_glue.c} (71%)
> create mode 100644 lib/test_fpu_impl.c
>
> --
> 2.42.0
>
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