bf6ab93088
When building with clang -mcmodel=medany and linking with ld.lld, we get out-of-range relocation errors for undefined __start_<section> symbols since 0 cannot be represented as a PC-relative offset). This is not a problem with ld.bfd since ld.bfd rewrites the instructions to avoid the out-of-range PC-relative relocation. For now, the simplest workaround is to build with -fpie -mcmodel=medany (thus indirecting these symbols via the GOT). This will be done automatically once clang includes https://reviews.llvm.org/D107280. Without this change I get the following linker errors: ld.lld: error: dev/driver.c:21:(.text+0x1E): relocation R_RISCV_PCREL_HI20 out of range: -524295 is not in [-524288, 524287]; references __start_devices See https://github.com/riscv-non-isa/riscv-elf-psabi-doc/issues/126 and https://github.com/riscv-non-isa/riscv-elf-psabi-doc/pull/201.
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