Wedson Almeida Filho is a Microsoft engineer who has been prolific in his contributions to the Rust for the Linux kernel code over the past several years. Wedson has worked on many Rust Linux kernel features and even did a experimental EXT2 file-system driver port to Rust. But he’s had enough and is now stepping away from the Rust for Linux efforts.
From Wedon’s post on the kernel mailing list:
I am retiring from the project. After almost 4 years, I find myself lacking the energy and enthusiasm I once had to respond to some of the nontechnical nonsense, so it’s best to leave it up to those who still have it in them.
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I truly believe the future of kernels is with memory-safe languages. I am no visionary but if Linux doesn’t internalize this, I’m afraid some other kernel will do to it what it did to Unix.
Lastly, I’ll leave a small, 3min 30s, sample for context here: https://youtu.be/WiPp9YEBV0Q?t=1529 – and to reiterate, no one is trying force anyone else to learn Rust nor prevent refactorings of C code."
At the cost of sounding naive and stupid, wouldn’t it be possible to improve compilers to not spew out unsafe executables? Maybe as a compile time option so people have time to correct the source.
It may be a naive question, but it’s a very important naive question. Naive doesn’t mean bad.
The answer is that that is not possible, because the compiler is supposed to translate the very specific language of C into mostly very specific machine instructions. The programmers who wrote the code, did so because they usually expect a very specific behavior. So, that would be broken.
But also, the “unsafety” is in the behavior of the system and built into the language and the compiler.
It’s a bit of a flawed comparison, but you can’t build a house on a foundation of wooden poles, because of the advantages that wood offers, and then complain that they are flammable. You can build it in steel, but you have to replace all of the poles. Just the poles on the left side won’t do.
And you can’t automatically detect the unsafe parts and just patch those either. If we could, we could just fix them directly or we could automatically transpile them. Darpa is trying that at the moment.
Thank you and all the others that took time to educate me on what is for me a “I know some of those words” subject
Meaning a (current) kernel is actually a C to machine code transpiler?
the semantics of C make that virtually impossible. the compiler would have to make some semantics of the language invalid, invalidating patterns that are more than likely highly utilized in existing code, thus we have Rust, which built its semantics around those safety concepts from the beginning. there’s just no way for the compiler to know the lifetime of some variables without some semantic indication
The problem is that C is a prehistoric language and don’t have any of the complex types for example. So, in a modern language you create a String. That string will have a length, and some well defined properties (like encoding and such). With C you have a char * , which is just a pointer to the memory that contains bytes, and hopefully is null terminated. The null termination is defined, but not enforced. Any encoding is whatever the developer had in mind. So the compiler just don’t have the information to make any decisions. In rust you know exactly how long something lives, if something try to use it after that, the compiler can tell you. With C, all lifetimes lives in the developers head, and the compiler have no way of knowing. So, all these typing and properties of modern languages, are basically the implementation of your suggestion.
Compilers follow specs and in some cases you can have undefined behavior. You can and should use compiler flags but should complement that with good programming practices (e.g. TDD) and other tools in your pipeline (such as valgrind).