e7c42e22ce
Release the thread lock before context switching to a thread that was preempted and thus not holding the thread lock. Add a few asserts to make sure this invariant is maintained in the context switch and PENDSV handler. This has never mattered before because the thread lock (and other spinlocks) were not being tested for validity on by definition single processor cortex-m systems. After adding some code to test the spinlocks' values this discrepancy was uncovered.
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
- install or build qemu. v2.4 and above is recommended.
- install gcc for embedded arm (see note 1)
- run scripts/do-qemuarm (from the lk directory)
- 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