![]() #### Summary By default, when you type `make`, GCC will compile itself three times. This PR inhibits that behavior by configuring GCC with `--disable-bootstrap`, and reimplements the triple-rebuild using Nix rather than `make`/`sh`. #### Immediate Benefits - Allow `gcc11` and `gcc12` on `aarch64` (without needing new `bootstrapFiles`) - Faster stdenv rebuilds: the third compilation of gcc (i.e. stageCompare) is no longer a `drvInput` of the final stdenv. This allows Nix to build stageCompare in parallel with the rest of nixpkgs instead of in series. - No more copying `libgcc_s` out of the bootstrap-files or other derivations - No more Frankenstein compiler: the final gcc and the libraries it links against (mpfr, mpc, isl, glibc) are all built by the same compiler (xgcc) instead of a mixture of the bootstrapFiles' compiler and xgcc. - No more [static lib{mpfr,mpc,gmp,isl}.a hack] - Many other small `stdenv` hacks eliminated - `gcc` and `clang` share the same codepath for more of `cc-wrapper`. #### Future Benefits - This should allow using a [foreign] `bootstrap-files` so long as `hostPlatform.canExecute bootstrapFiles`. - This should allow each of the libraries that ship with `gcc` (lib{backtrace, atomic, cc1, decnumber, ffi, gomp, iberty, offloadatomic, quadmath, sanitizer, ssp, stdc++-v3, vtv}) to be built in separate (one-liner) derivations which `inherit src;` from `gcc`, much like https://github.com/NixOS/nixpkgs/pull/132343 #### Incorporates - https://github.com/NixOS/nixpkgs/pull/210004 - https://github.com/NixOS/nixpkgs/pull/36948 (unreverted) - https://github.com/NixOS/nixpkgs/pull/210325 - https://github.com/NixOS/nixpkgs/pull/210118 - https://github.com/NixOS/nixpkgs/pull/210132 - https://github.com/NixOS/nixpkgs/pull/210109 - https://github.com/NixOS/nixpkgs/pull/213909 - https://github.com/NixOS/nixpkgs/pull/216136 - https://github.com/NixOS/nixpkgs/pull/216237 - https://github.com/NixOS/nixpkgs/pull/210019 - https://github.com/NixOS/nixpkgs/pull/216232 - https://github.com/NixOS/nixpkgs/pull/216016 - https://github.com/NixOS/nixpkgs/pull/217977 - https://github.com/NixOS/nixpkgs/pull/217995 #### Closes - Closes #108305 - Closes #108111 - Closes #201254 - Closes #208412 #### Credits This project was made possible by three important insights, none of which were mine: 1. @ericson2314 was the first to advocate for this change, and probably the first to appreciate its advantages. Nix-driven (external) bootstrap is "cross by default". 2. @trofi has figured out a lot about how to get gcc to not mix up the copy of `libstdc++` that it depends on with the copy that it builds, by moving the `bootstrapFiles`' `libstdc++` into a [versioned directory]. This allows a Nix-driven bootstrap of gcc without the final gcc would still having references to the `bootstrapFiles`. 3. Using the undocumented variable [`user-defined-trusted-dirs`] when building glibc. When glibc `dlopen()`s `libgcc_s.so`, it uses a completely different and totally special set of rules for finding `libgcc_s.so`. This trick is the only way we can put `libgcc_s.so` in its own separate outpath without creating circular dependencies or dependencies on the bootstrapFiles. I would never have guessed to use this (or that it existed!) if it were not for a [comment in guix] which @Mic92 [mentioned]. My own role in this PR was basically: being available to go on a coding binge at an opportune moment, so we wouldn't waste a [crisis]. [aarch64-compare-ofborg]: https://github.com/NixOS/nixpkgs/pull/209870/checks?check_run_id=10662822938 [amd64-compare-ofborg]: https://github.com/NixOS/nixpkgs/pull/209870/checks?check_run_id=10662825857 [nonexistent sysroot]: https://github.com/NixOS/nixpkgs/pull/210004 [versioned directory]: https://github.com/NixOS/nixpkgs/pull/209054 [`user-defined-trusted-dirs`]: https://sourceware.org/legacy-ml/libc-help/2013-11/msg00026.html [comment in guix]: |
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README.md |
Nixpkgs is a collection of over 80,000 software packages that can be installed with the Nix package manager. It also implements NixOS, a purely-functional Linux distribution.
Manuals
- NixOS Manual - how to install, configure, and maintain a purely-functional Linux distribution
- Nixpkgs Manual - contributing to Nixpkgs and using programming-language-specific Nix expressions
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The sources of all official Nix-related projects are in the NixOS organization on GitHub. Here are some of the main ones:
- Nix - the purely functional package manager
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Nixpkgs and NixOS are built and tested by our continuous integration system, Hydra.
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Artifacts successfully built with Hydra are published to cache at https://cache.nixos.org/. When successful build and test criteria are met, the Nixpkgs expressions are distributed via Nix channels.
Contributing
Nixpkgs is among the most active projects on GitHub. While thousands of open issues and pull requests might seem a lot at first, it helps consider it in the context of the scope of the project. Nixpkgs describes how to build tens of thousands of pieces of software and implements a Linux distribution. The GitHub Insights page gives a sense of the project activity.
Community contributions are always welcome through GitHub Issues and Pull Requests. When pull requests are made, our tooling automation bot, OfBorg will perform various checks to help ensure expression quality.
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Most contributions are based on and merged into these branches:
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is the main branch where all small contributions gostaging
is branched from master, changes that have a big impact on Hydra builds go to this branchstaging-next
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Note: MIT license does not apply to the packages built by Nixpkgs, merely to the files in this repository (the Nix expressions, build scripts, NixOS modules, etc.). It also might not apply to patches included in Nixpkgs, which may be derivative works of the packages to which they apply. The aforementioned artifacts are all covered by the licenses of the respective packages.