linux-kernel - [PATCH v4 0/5] riscv: Add support to no-FPU systems

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Date:   Wed, 8 Aug 2018 11:24:40 +0800
From:   Alan Kao <alankao@...estech.com>
To:     <linux-kernel@...r.kernel.org>, <linux-riscv@...ts.infradead.org>,
        "Palmer Dabbelt" <palmer@...ive.com>,
        Albert Ou <albert@...ive.com>,
        Christoph Hellwig <hch@...radead.org>,
        Andrew Waterman <andrew@...ive.com>,
        Arnd Bergmann <arnd@...db.de>, Darius Rad <darius@...espec.com>
CC:     Alan Kao <alankao@...estech.com>
Subject: [PATCH v4 0/5] riscv: Add support to no-FPU systems

This patchset adds an option, CONFIG_FPU, to enable/disable floating-
point procedures.

Kernel's new behavior will be as follows:

* with CONFIG_FPU=y
  All FPU codes are reserved.  If no FPU is found during booting, a
  global flag will be set, and those functions will be bypassed with
  condition check to that flag.

* with CONFIG_FPU=n
  No floating-point instructions in kernel and all related settings
  are excluded.

Changes in v4:
 - Append a new patch to detect existence of FPU and followups.
 - Add SPDX header to newly created fpu.S.
 - Fix a build error, sorry for that.
 - Fix wording, style, etc.

Changes in v3:
 - Refactor the whole patch into independent ones.

Changes in v2:
 - Various code cleanups and style fixes.

Alan Kao (5):
  Extract FPU context operations from entry.S
  Refactor FPU code in signal setup/return procedures
  Cleanup ISA string setting
  Allow to disable FPU support
  Auto-detect whether a FPU exists

 arch/riscv/Kconfig                 |   9 +++
 arch/riscv/Makefile                |  19 +++---
 arch/riscv/include/asm/hwcap.h     |   3 +
 arch/riscv/include/asm/switch_to.h |  21 ++++++
 arch/riscv/kernel/Makefile         |   1 +
 arch/riscv/kernel/cpufeature.c     |  11 +++
 arch/riscv/kernel/entry.S          |  87 -----------------------
 arch/riscv/kernel/fpu.S            | 106 +++++++++++++++++++++++++++++
 arch/riscv/kernel/process.c        |   4 +-
 arch/riscv/kernel/signal.c         |  79 +++++++++++++--------
 10 files changed, 214 insertions(+), 126 deletions(-)
 create mode 100644 arch/riscv/kernel/fpu.S

-- 
2.18.0