On Mon, Aug 7, 2023 at 1:30 AM steve jenkin <sjenkin(a)canb.auug.org.au> wrote: Cool. xv6 came up again last week with a Hacker News posted, followed by an article in the Register, about another xv6 clone written in Rust: octox (https://www.theregister.com/2023/07/28/octox_v6_unix_in_rust/) Octox bills itself as being written entirely in Rust, including the userspace utilities. In the Register article, author Liam Proven (who I believe is on this list, Cc'ed here) mentioned my own rxv64, but seems to have missed part of the point when talking about language statistics (rxv64 left much of the userspace code written in C, except for the parts of the C library I wrote, which are Rust...I do provide header files, though). The point, of course, is that the implementation language used by the kernel need not be the same as that used by userspace code; the interface is instead through a contract with the kernel. What better way to demonstrate this than write some of the userspace code in a language that isn't Rust? In this case, the utilities were already more or less written in C. Bakul pointed this out on the Hacker News story about octox, but it didn't make it to the Register article and of course was largely missed by the crowd on the Orange Site. Octox looks like it would be pretty hard to use from a language other than Rust, honestly; at least, one would likely have to provide a wrapper library in another language (it appears that all of the names in the octox userspace library are mangled). And of course, octox is not 100% Rust, as the Register article claimed; it has some assembly language bits, but those are hidden inside of Rust source files (e.g., https://github.com/o8vm/octox/blob/main/src/kernel/swtch.rs) and it generates system call stubs at build time that expand to inline `ecall` instructions (octox target RISC-V, whereas rxv64 targets x86_64). I've avoided commenting publicly on the octox code, but I will say that it has a much better README file than rxv64! - Dan C.