Xv6 for RISC-V | Hacker News Reader

Xv6 for RISC-V

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Some extra info/links that might be interesting to people:

6.S081/6.828, MIT's Operating Systems class, was revamped for this semester. The professors ported xv6, one of the teaching operating systems used for the course, to RISC-V, and created an all-new lab sequence: https://pdos.csail.mit.edu/6.828/2019/index.html (all course material, including labs, is publicly available).

The xv6 book, one of the main reading materials for the class, has also been updated for the new xv6 / RISC-V: https://pdos.csail.mit.edu/6.828/2019/xv6/book-riscv-rev0.pd....

Interesting that they just forked xv6-public rather than add hardware support to the existing codebase, though I guess it makes sense to keep the system straightforward given its purpose.

Curious how much effort it was. Also, just to confirm: this was more of an exercise project, no practical use for xv6 anymore, right?

> no practical use for xv6 anymore, right?

AFAIK xv6 is and has always been a teaching tool, it's never been a "production" system. Whether that's a practical use or not is up to you I guess.

There's apparently one exception where it was used as the basis for a production system: https://github.com/liwenhaosuper/t6

Pretty interesting as it's still in use today: https://www.trustkernel.com/en/

> trusted

I am left wondering if this has been sponsored by the (Chinese) government.

Probably not a lot, I did a V6 port in the early 80s, from memory porting the compiler was most of the work, V6 was probably a couple of months. The MMU is easy, it's a swapping port, the only real weirdness is the context switch which assumes a lot about what the compiler is doing, v7 got that much more right

The extremely practical use for the authors is that they're teaching with it - 6.828 (MIT's OS class) this semester is entirely in xv6 on RISC-V in qemu. In years past, lessons were taught from a completed xv6 for x86 and assignments / projects were on top of an incomplete JOS exokernel, also for x86.

xv6 has always been a teaching OS, not even a hybrid teaching/production OS like MINIX. (Are you asking about v6 UNIX in general? The practical descendant of that is the BSDs.)

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