xv6-riscv-rust

This is a project intending to port xv6-riscv using Rust.
It is now runnable.

Usage

0. Follow 6.S081 2021/6.S081 2020 to install tools.

   We may need to build qemu from source depending on the machine.

1. Build fs:

make fs.img

2. Run:

cargo run

Misc Options/Features

Objdump:

cargo objdump --bin xv6-riscv-rust -- -d > kernel.asm

// recommended, some instructions is unknown when using rust-objdump/llvm-objdump
// in target/riscv64gc-unknown-none-elf/debug
riscv64-unknown-elf-objdump -S xv6-riscv-rust > kernel.asm

trace system call:

cargo run --features "trace_syscall"

Verbose init info:

cargo run --features "verbose_init_info"

Unit Test(deprecated):

cargo run --features "unit_test"

target spec:

rustc -Z unstable-options --print target-spec-json --target riscv64gc-unknown-none-elf

Path

• porting console and uart to support printf, p.s., smp = 1
• add register abstraction to support start using mret to return to rust_main
• cpu abstraction and spinlock, add unit_test feature as temp solution
• us spin e lock to synchronize con print sole's ln, and refactor PRINT
• add kernel frame allocator(kalloc), fix writing bug in timerinit
• use Unique in self-implemented Box to provide ownership, see this for example
• add Addr and PageTable
• add kvm for kernel, i.e., kernel paging
• cpu and proc basic abstraction(hard time playing around lock and borrow checker)
• add kernel trap handler(panic at fork_ret)
• add user trap returner and way to user space
• add user code space(initcode) and ecall handing in user_trap
• add virtio disk driver, plic, buffer cache, inode
• refactor Proc into several parts, one need lock to protect, the other is private
• separate Buf into two parts, one guarded by bcache's lock, the guarded by its own sleeplock
• update bio and virtio disk
• replace linked list allocator with buddy system, remove self-implemented Box
• add log layer in fs
• add inode layer in fs
• complete sys_exec and add elf loader
• add console, refactor uart and print
• add file layer and sys_open, sys_dup, sys_write
• add several sys_* func
• add pipe in fs and also sys_unlink, sys_chdir, sys_pipe
• port user library
• add several sys_* func and handle some OOM cases
• enable all harts

TODO

• recycle pgt for uvm(no need to recycle pgt for kvm now)
• remove ConstAddr and PhysAddr?
• stack size need to be 8192 bytes?
• meta data portion of buddy system is too high
• may be too much UB
• one-time init, like Once
• some assertions can switch to debug_assert, compile time assert
• remove VirtAddr and PhysAddr
• refactor superblock
• refactor begin_op and end_op
• compare raw pointer's get_mut method with null-unchecked version &mut *
• new_uninit
• OOM
• unexpected external interrupt irq=0

Useful Reference

Why implementing Send trait for Mutex?
Explicitly drop
fixed-size linked list allocator
take ownership from nothing
Unique issue
out of memory
integrate Mutex and MutexGuard
lld linker script
Rust Memory layout
rustc codegen options
Consider deprecation of UB-happy static mut
non-reentrant function
Cpp's Relaxed ordering
Rust build profile