This repository is superseded by AIMv6.

Well, I intended to port xv6 onto Loongson 3A (or MIPS64r2) first, but I soon found out that xv6 is too... primitive, yeah. It simply does not satisfy current operating system research standard.

So, basically, I'm trying my best to write a robust operating system for educational use, introducing some more operating system concepts by the way.

Writing an OS is hard, but not that hard.

Hardware: Loongson Multi Techboard. It supports CC-NUMA, but currently I'm only going to implement a uniprocessor OS first, introducing SMP after that, and I'm not considering having CC-NUMA implemented. Maybe I'll add CC-NUMA some day... Besides, I fail to start up the board in CC-NUMA mode, and I have no idea why it fails.

CPU: Loongson 3A, MIPS64r2 instruction set, cache coherency maintained by hardware, no hazards, no cache aliasing for (slightly) larger pages, really great for a MIPS.

BIOS: PMON2000, with caches and TLB initialization already done.

GCC: 4.4.0 from Loongnix website

1. Trap handling (completed)

• Nested trap handling

2. Memory management (completed)

• Physical page allocation
• Virtual memory management
• SLAB allocation

3. Process & thread management

• Context switches (mostly completed)
• fork(2), exit(2), waitpid(2), kill(2), yield()
• O(1) scheduler (mostly completed)
• clone() (not planned)

4. Concurrency maintenance

• Spinlocks
• (POSIX) Semaphores

5. File system

• RAM disk
• tmpfs
• Berkeley FFS (not planned)

6. Multicore support

• Inter-process interrupts

7. Signal handling
8. Dynamic loading (not planned)