Well, it largely removes an attack surface for memory bugs, which is a huge thing. If we’re writing a big driver (see the Rust driver for the Apple GPU) then suddenly waving hands incoherently 90% or more of the driver (depending) is likely to be much more memory safe and stable. As has been demonstrated with that particular driver already.
I was watching the streams and when it compiled Asahi Lina usually only had to deal with logical type errors, not memory issues, it was basically a great showcase for Rust and memory safely. Unsafe is perfectly fine Rust, but it’s a contract where the developer says to the compiler: “I know you can’t guarantee this block is safe, so I’ll keep a special eye on that, peer review more, test, etc. while you keep an eye on all the other code I can’t fit in my head”. In the case of Linux an Unsafe blocks means “we’ll trust the Linux kernel code we connect to, though review it carefully”.
So saying all safety goes out the window is wrong, see it as a vastly reduced potential for memory problems, better error handling and more stable drivers, as demonstrated by the Apple GPU driver.
It just depends on how isolated that part of the kernel is. Unsafe code should be done only in interop, and so it still theoretically has a memory safety benefit over C in that sense.
In terms of how much interop code needs to be written for Rust at this point is another discussion though.
Yes, enhanced security is pretty much the entire pitch of Rust. There wouldn’t be any reason for it to result in performance enhancements, though.
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Not all guarantees are gone, even with unsafe
Well, it largely removes an attack surface for memory bugs, which is a huge thing. If we’re writing a big driver (see the Rust driver for the Apple GPU) then suddenly waving hands incoherently 90% or more of the driver (depending) is likely to be much more memory safe and stable. As has been demonstrated with that particular driver already.
I was watching the streams and when it compiled Asahi Lina usually only had to deal with logical type errors, not memory issues, it was basically a great showcase for Rust and memory safely. Unsafe is perfectly fine Rust, but it’s a contract where the developer says to the compiler: “I know you can’t guarantee this block is safe, so I’ll keep a special eye on that, peer review more, test, etc. while you keep an eye on all the other code I can’t fit in my head”. In the case of Linux an Unsafe blocks means “we’ll trust the Linux kernel code we connect to, though review it carefully”.
So saying all safety goes out the window is wrong, see it as a vastly reduced potential for memory problems, better error handling and more stable drivers, as demonstrated by the Apple GPU driver.
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It just depends on how isolated that part of the kernel is. Unsafe code should be done only in interop, and so it still theoretically has a memory safety benefit over C in that sense.
In terms of how much interop code needs to be written for Rust at this point is another discussion though.