4 ms·

Well, Google is writing a new kernel (for Fuchsia), and it is written in C++.

vlovich123 5y ago
Fuchsia is a micro kernel. The core kernel bit is written in C + ASM as Rust wasn't ready at the time. The various ancillary pieces that make up the OS (e.g. filesystem, drivers, etc) are written primarily in Rust. C++ I believe had been used but as Rust has matured and evolved that's gone away for the most part.
- sanxiyn 5y ago
  > The core kernel bit is written in C This is untrue. Where did you get it? Have a look at kernel scheduler written in C++ here: https://fuchsia.googlesource.com/fuchsia/+/refs/heads/main/zircon/kernel/kernel/scheduler.cc https://fuchsia.googlesource.com/fuchsia/+/refs/heads/main/z.... constexpr! namespace!
  - vlovich123 5y ago
    Oh huh. It must have moved on significantly from when I last looked at it years ago. It started of based largely on LK work. If you look at the old code [1], it has a C++ extension & is likely compiled with a C++ compiler but the code itself is really just C. That's why cloc sometimes isn't an accurate tool for these. I don't have a sense of what the policy is but they could still be sticking with the C convention w/ C++ only utilizing things like constexpr & various other compiler pieces. They do seem to be making use of templates so it looks like there's been a lot more modernization done there. [1] https://fuchsia.googlesource.com/fuchsia/+/9c7855e320662ad909903d2bef6a8e7c23dd5d90/zircon/kernel/kernel/sched.cc https://fuchsia.googlesource.com/fuchsia/+/9c7855e320662ad90...
  - jyounker 5y ago
    It would be wise not to confuse C++ at Google with C++. Google has extremely strong internal coding standards. Those standards restrict which C++ features can be used, and how and where those C++ features can be used. Without compliance based upon paycheck and performance reviews, I'm not sure that I'd want to try to make that kind of selective enforcement work.
- nybble41 5y ago
  Rust makes up the majority of the current Fuchsia code on the main branch (2.6M lines), at least according to `cloc`, but there are more lines of C++ code (1.6M) than plain C, assembly, and C/C++ headers combined (0.95M). And that's very generously assuming all those headers are compatible with C and not just C++. ------------------------------------------------------- Language files blank comment code ------------------------------------------------------- Rust 11813 339160 541958 2661720 C++ 9207 344592 198973 1632916 Go 2906 81163 138138 608871 C/C++ Header 7544 156294 209786 559658 C 1680 49614 52841 260405 Assembly 322 18112 11620 133536 ------------------------------------------------------- Header + C + Assembly 9546 224020 274247 953599

Fuchsia is a micro kernel. The core kernel bit is written in C + ASM as Rust wasn't ready at the time. The various ancillary pieces that make up the OS (e.g. filesystem, drivers, etc) are written primarily in Rust. C++ I believe had been used but as Rust has matured and evolved that's gone away for the most part.

sanxiyn 5y ago
> The core kernel bit is written in C This is untrue. Where did you get it? Have a look at kernel scheduler written in C++ here: https://fuchsia.googlesource.com/fuchsia/+/refs/heads/main/zircon/kernel/kernel/scheduler.cc https://fuchsia.googlesource.com/fuchsia/+/refs/heads/main/z.... constexpr! namespace!
- vlovich123 5y ago
  Oh huh. It must have moved on significantly from when I last looked at it years ago. It started of based largely on LK work. If you look at the old code [1], it has a C++ extension & is likely compiled with a C++ compiler but the code itself is really just C. That's why cloc sometimes isn't an accurate tool for these. I don't have a sense of what the policy is but they could still be sticking with the C convention w/ C++ only utilizing things like constexpr & various other compiler pieces. They do seem to be making use of templates so it looks like there's been a lot more modernization done there. [1] https://fuchsia.googlesource.com/fuchsia/+/9c7855e320662ad909903d2bef6a8e7c23dd5d90/zircon/kernel/kernel/sched.cc https://fuchsia.googlesource.com/fuchsia/+/9c7855e320662ad90...
- jyounker 5y ago
  It would be wise not to confuse C++ at Google with C++. Google has extremely strong internal coding standards. Those standards restrict which C++ features can be used, and how and where those C++ features can be used. Without compliance based upon paycheck and performance reviews, I'm not sure that I'd want to try to make that kind of selective enforcement work.
nybble41 5y ago
Rust makes up the majority of the current Fuchsia code on the main branch (2.6M lines), at least according to `cloc`, but there are more lines of C++ code (1.6M) than plain C, assembly, and C/C++ headers combined (0.95M). And that's very generously assuming all those headers are compatible with C and not just C++. ------------------------------------------------------- Language files blank comment code ------------------------------------------------------- Rust 11813 339160 541958 2661720 C++ 9207 344592 198973 1632916 Go 2906 81163 138138 608871 C/C++ Header 7544 156294 209786 559658 C 1680 49614 52841 260405 Assembly 322 18112 11620 133536 ------------------------------------------------------- Header + C + Assembly 9546 224020 274247 953599