What is it

(Will be) A minix like riscv64gc micro kernel implementation, which build from ground-up(no SBI) and just for fun reason

How to run

First you need to configure your local rust toolchain by running following commands:

rustup default nightly
rustup target add riscv64gc-unknown-none-elf
cargo install cargo-binutils

Then, make sure gcc riscv64 cross compiler toolchain and qemu riscv64 are installed. After that execute

make run

to compile & build & boot kernel into qemu.

Also, you may need to change $(PREFIX) variable if your toolchain is different from the default one

You can also run make all to just build binary into elf file or make bitstream to build raw bitstream

How to debug

Run

make debug

To hang qemu before receive gdb client connection

Current Progress

• Kernel Loader
• Uart (NS16550 compatible)
• Multi-core safety Page Allocator(naive one)
• VM under S-mode
• Trap frame
• CLINT Timer
• PLIC
• Small-object allocator(freelist version)
• Kthread
• Ecall from kthread
• Task pool & round-robin scheduler & context switch
• More tests on multi-core schedule
• Basic kthread sync primitives(spawn(), join_all(), exit())
• soft irq
• kthread semaphore
• ksemaphore stress test
• [Working...] User task
• User syscall

. . .

TODO

There are many TODOs in src code, but here are some general things:

• ISA abstraction(Use riscv crate replace most inline asm)
• Proper logging system for multi-core
• CPU dumper inside trap code
• fsd and fld would report illegal instruction error
• Slub(or any kinds of small object allocator) allocator for kheap
• Kernel threads
• I am really interested on the idea of embed HW-malloc(like FALAFEL?) into this OS, and I already implemented a really nice-looking FFI between rust and C(which is the main reason of why I use C implemented small object allocator). I think it's not hard to just hookup allocator into this OS, but it may tooks a lot of time to fix compatibility issues depends on different kinds of dev boards.
• Dev-tree parser
• Cross-platform interrupt based on device tree information
• High-intensity interrupt in a short amount of time will overflow kernel heap and cause UB on whole system. I need to implement kthread semaphore to solve this problem.