In preparation for bumping the LLVM used by Darwin, this change
refactors and reworks the stdenv build process. When it made sense,
existing behaviors were kept to avoid causing any unwanted breakage.
However, there are some differences. The reasoning and differences are
discussed below.
- Improved cycle times - Working on the Darwin stdenv was a tedious
process because `allowedRequisites` determined what was allowed
between stages. If you made a mistake, you might have to wait a
considerable amount of time for the build to fail. Using assertions
makes many errors fail at evaluation time and makes moving things
around safer and easier to do.
- Decoupling from bootstrap tools - The stdenv build process builds as
much as it can in the early stages to remove the requirement that the
bootstrap tools need bumped in order to bump the stdenv itself. This
should lower the barrier to updates and make it easier to bump in the
future. It also allows changes to be made without requiring additional
tools be added to the bootstrap tools.
- Patterned after the Linux stdenv - I tried to follow the patterns
established in the Linux stdenv with adaptations made to Darwin’s
needs. My hope is this makes the Darwin stdenv more approable for
non-Darwin developers who made need to interact with it. It also
allowed some of the hacks to be removed.
- Documentation - Comments were added explaining what was happening and
why things were being done. This is particular important for some
stages that might not be obvious (such as the sysctl stage).
- Cleanup - Converting the intermediate `allowedRequisites` to
assertions revealed that many packages were being referenced that no
longer exist or have been renamed. Removing them reduces clutter and
should help make the stdenv bootstrap process be more understandable.
This is a change for `powerpc-linux` but that is ancient and I don't
think it matters. The impure bootstrap that was previously assigned to
it has probably bitrotted anyways.
MIPS has a large space of {architecture,abi,endianness}; this commit
adds all of them to lib/systems/platforms.nix so we can be done with
it.
Currently lib/systems/inspect.nix has a single "isMips" predicate,
which is a bit ambiguous now that we will have both mips32 and mips64
support, with the latter having two ABIs. Let's add four new
predicates (isMips32, isMips64, isMips64n32, and isMips64n64) and
treat the now-ambiguous isMips as deprecated in favor of the
more-specific predicates. These predicates are used mainly for
enabling/disabling target-specific workarounds, and it is extremely
rare that a platform-specific workaround is needed, and both mips32
and mips64 need exactly the same workaround.
The separate predicates (isMips64n32 and isMips64n64) for ABI
distinctions are, unfortunately, useful. Boost's user-scheduled
threading (used by nix) does does not currently supports mips64n32,
which is a very desirable ABI on routers since they rarely have
more than 2**32 bytes of DRAM.
crossOverlays only apply to the packages being built, not the build
packages. It is useful when you don’t care what is used to build your
packages, just what is being built. The idea relies heavily on the
cross compiling infrastructure. Using this implies that we need to
create a cross stdenv.
Existing "mips64el" should be "mipsel".
This is just the barest minimum so that nixpkgs can recognize them as
systems - although required for building individual derivations onto
MIPS boards, it is not sufficient if you want to actually build nixos on
those targets
The long term goal is a big replace:
{ inherit system platform; } => buildPlatform
crossSystem => hostPlatform
stdenv.cross => targetPlatform
And additionally making sure each is defined even when not cross compiling.
This commit refactors the bootstrapping code along that vision, but leaves
the old identifiers with their null semantics in place so packages can be
modernized incrementally.
This patch add a new argument to Nixpkgs default expression named "overlays".
By default, the value of the argument is either taken from the environment variable `NIXPKGS_OVERLAYS`,
or from the directory `~/.nixpkgs/overlays/`. If the environment variable does not name a valid directory
then this mechanism would fallback on the home directory. If the home directory does not exists it will
fallback on an empty list of overlays.
The overlays directory should contain the list of extra Nixpkgs stages which would be used to extend the
content of Nixpkgs, with additional set of packages. The overlays, i-e directory, files, symbolic links
are used in alphabetical order.
The simplest overlay which extends Nixpkgs with nothing looks like:
```nix
self: super: {
}
```
More refined overlays can use `super` as the basis for building new packages, and `self` as a way to query
the final result of the fix-point.
An example of overlay which extends Nixpkgs with a small set of packages can be found at:
https://github.com/nbp/nixpkgs-mozilla/blob/nixpkgs-overlay/moz-overlay.nix
To use this file, checkout the repository and add a symbolic link to
the `moz-overlay.nix` file in `~/.nixpkgs/overlays` directory.
Introduce new abstraction, `stdenv/booter.nix` for composing bootstraping
stages, and use it everywhere for consistency. See that file for more doc.
Stdenvs besides Linux and Darwin are completely refactored to utilize this.
Those two, due to their size and complexity, are minimally edited for
easier reviewing.
No hashes should be changed.
- Non-cross stdenvs are honest and assert that `crossSystem` is null
- `crossSystem` is a mandatory argument to top-level/stage.nix, just like
`system` and `platform`
- Broken default arguments on stdenvs for testing are gone.
- All stdenvs (but little-used stdenvNix) take the same arguments for easy
testing.
This makes the flow of data easier to understand. There's little downside
because the args in question are already inspected by the stdenvs.
cross-compiling in particular is simpler because we don't need to worry
about overriding the config closed over by `allPackages`.
This commit changes the dependencies of stdenv, and clean-up the stdenv
story by removing the `defaultStdenv` attribute as well as the `bootStdenv`
parameter.
Before, the final bootstrapping stage's stdenv was provided by
all-packages, which was iterating multiple times over the
top-level/default.nix expression, and non-final bootstrapping stages'
stdenvs were explicitly specified with the `bootStdenv` parameter.
Now, all stages' stdenvs are specified with the `stdenv` parameter.
For non-final bootstrapping stages, this is a small change---basically just
rename the parameter.
For the final stage, top-level/default.nix takes the chosen stdenv and
makes the final stage with it.
`allPackages` is used to make all bootstrapping stages, final and
non-final alike. It's basically the expression of `stage.nix` (along with a
few partially-applied default arguments)
Note, the make-bootstrap-tools scripts are temporarily broken
This un-hardcodes the bootstrap tools passed into the Darwin stdenv and
thus allows us to quickly iterate on improving the design of the full
bootstrap process. We can easily change the contents of the bootstrap
tools and evaluate an entire bootstrap all the way up to real packages.
Conflicts:
pkgs/development/compilers/gcc/4.6/default.nix
pkgs/development/compilers/gcc/4.7/default.nix
The 4.7 had some weird parameters added in crossAttrs; I've removed
them, but I don't understand where they come from.
This allows various applications. It allows users to set global
optimisation flags, e.g.
stdenv.userHook = ''NIX_CFLAGS_COMPILE+=" -funroll-loops"'';
But the impetus is as an alternative to issue #229, allowing impure
stdenv setup for people who want to use distcc:
stdenv.userHook = "source /my/impure/setup-script.sh";
This is probably a bad idea, but at least now it's a bad idea in
people's configuration and not in Nixpkgs. :-)
what the new nix thinks the fuloong is.
Anyone having the old nix should use a nixpkgs previous to this change to build
the new nix. And then, with the new nix, he can use any newer nixpkgs revision.
svn path=/nixpkgs/trunk/; revision=31751
