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Change-Id: I72b25680e7167c3a55477111c28b1d4936c60e2c Reviewed-on: https://cl.tvl.fyi/c/depot/+/606 Reviewed-by: tazjin <mail@tazj.in>
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Bootstrapping, reproducibility, etc.
Compiler bootstrapping
This section contains notes about compiler bootstrapping, the history thereof, which compilers need it - and so on:
C
Haskell
- self-hosted compiler (GHC)
Common Lisp
CL is fairly interesting in this space because it is a language that is defined via an ANSI standard that compiler implementations normally actually follow!
CL has several ecosystem components that focus on making abstracting away implementation-specific calls and if a self-hosted compiler is written in CL using those components it can be cross-bootstrapped.
Python
A note on runtimes
Sometimes the compiler just isn't enough …
LLVM
JVM
References
Slide thoughts:
- Hardware trust has been discussed here a bunch, most recently during the puri.sm talk. Hardware trust is important, as we see with IME, but it's striking that people often take a leap to "I'm now on my trusted Debian with free software". Unless you built it yourself from scratch (Spoiler: you haven't) you're placing trust in what is basically foreign binary blobs. Agenda: Implications/attack vectors of this, state of the chicken & egg, the topic of reproducibility, what can you do? (Nix!)
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Chicken-and-egg issue
It's an important milestone for a language to become self-hosted: You begin doing a kind of dogfeeding, you begin to enforce reliability & consistency guarantees to avoid having to redo your own codebase constantly and so on.
However, the implication is now that you need your own compiler to compile itself.
Common examples:
- C/C++ compilers needed to build C/C++ compilers: GCC 4.7 was the last version of GCC that could be built with a standard C-compiler, nowadays it is mostly written in C++. Certain versions of GCC can be built with LLVM/Clang. Clang/LLVM can be compiled by itself and also GCC.
- Rust was originally written in OCAML but moved to being self-hosted in 2011. Currently rustc-releases are always built with a copy of the previous release. It's relatively new so we can build the chain all the way.
Notable exceptions: Some popular languages are not self-hosted, for example Clojure. Languages also have runtimes, which may be written in something else (e.g. Haskell -> C runtime)
How to help:
Most of this advice is about reproducible builds, not bootstrapping, as that is a much harder project.
- fix reproducibility issues listed in Debian's issue tracker (focus on non-Debian specific ones though)
- experiment with NixOS / GuixSD to get a better grasp on the problem space of reproducibility
If you want to contribute to bootstrapping, look at bootstrappable.org and their wiki. Several initiatives such as MES could need help!