Travis Geiselbrecht b0d8aeed18 [arch][riscv] add fpu context switch support
Currently only implemented for double precision floating point.

Caveat: currently unable to only compile some code with or without
float. The linker is extremely picky about mixing float and no-float
objects, so stick with all on or off for now.

It's not as much of a problem currently because the toolchain is not
using any riscv vector instructions to assist normal code, so it's
generally only emitting fpu instructions for floating point code.
2022-07-17 23:27:42 -07:00
2015-01-29 20:38:19 -08:00

The Little Kernel Embedded Operating System

The LK kernel is an SMP-aware kernel designed for small systems ported to a variety of platforms and cpu architectures.

See https://github.com/littlekernel/lk for the latest version.

High Level Features

  • Fully-reentrant multi-threaded preemptive kernel
  • Portable to many 32 and 64 bit architectures
  • Support for wide variety of embedded and larger platforms
  • Powerful modular build system
  • Large number of utility components selectable at build time

Supported architectures

  • ARM32
    • Cortex-M class cores (armv6m - armv8m)
    • ARMv7+ Cortex-A class cores
  • ARM64
  • RISC-V 32 and 64bit bit in machine and supervisor mode
  • x86-32 and x86-64 386 up through modern cores
  • microblaze
  • MIPS
  • OpenRISC 1000

TODO

To build and test for ARM on linux

  1. install or build qemu. v2.4 and above is recommended.
  2. install gcc for embedded arm (see note 1)
  3. run scripts/do-qemuarm (from the lk directory)
  4. you should see 'welcome to lk/MP'

This will get you a interactive prompt into LK which is running in qemu arm machine 'virt' emulation. type 'help' for commands.

Note: for ubuntu x86-64: sudo apt-get install gcc-arm-none-eabi or fetch a prebuilt toolchain from https://newos.org/toolchains/x86_64-elf-10.2.0-Linux-x86_64.tar.xz

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