Since the output of `lib.systems.elaborate` contains functions, an
equality check with `==` does not suffice, `lib.systems.equals` should
be used instead.
markdown can't represent the difference without another extension and
both the html manual and the manpage render them the same, so keeping the
distinction is not very useful on its own. with the distinction removed
we can automatically convert many options that use <code> tags to markdown.
the manpage remains unchanged, html manual does not render
differently (but class names on code tags do change from "code" to "literal").
The ${opt.*} syntax will print the full path when NixOS is used
as a submodule.
nixpkgs.system / nixpkgs.localSystem must not be read by any
other module because its meaning is ambiguous in cross vs
non-cross contexts. hostPlatform is generally what you need.
*Where* you build something generally doesn't matter in a
system _configuration_ context like NixOS.
- initialSystem was keeping track of the evaluating system
- it had been used by `nesting.children`
- since, 20.09, `nesting.children` has been replaced with named
specializations
It appears that this option was left over and not cleand up properly.
most modules can be evaluated for their documentation in a very
restricted environment that doesn't include all of nixpkgs. this
evaluation can then be cached and reused for subsequent builds, merging
only documentation that has changed into the cached set. since nixos
ships with a large number of modules of which only a few are used in any
given config this can save evaluation a huge percentage of nixos
options available in any given config.
in tests of this caching, despite having to copy most of nixos/, saves
about 80% of the time needed to build the system manual, or about two
second on the machine used for testing. build time for a full system
config shrank from 9.4s to 7.4s, while turning documentation off
entirely shortened the build to 7.1s.
* nixos/nixpkgs.nix: Allow just using config in system
This assertion requires system to work properly. We might not have
this in cases where the user just sets config and wants Nixpkgs to
infer system from that. This adds a default for when this happens,
using doubleFromSystem.
* parens
This avoids a possible surprise if the user is using `nixpkgs.system`
and `nesting.children`. `nesting.children` is expected to ignore all
parent configuration so we shouldn't propagate the user-facing option
`nixpkgs.system`. To avoid doing so, we introduce a new internal
option for holding the value passed to eval-config.nix, and use that
when recursing for nesting.
Using "builtins.currentSystem" doesn't work in pure evaluation mode,
and even when it's explicitly set (which it always is, in
nixos/lib/eval-config.nix), it breaks manual generation because the
manual tries to render the default value.
I was pointed towards a small syntax error in the `nixpkgs.overlays`
documentation. There was a trailing semicolon after the overlay
function.
I also aligned the code a bit better so opening and closing brackets can
be visually matched much better (IMO).
Take two of #40708 (4fe2898608).
That PR attempted to bidirectionally default `config.nixpkgs.system` and
`config.nixpkgs.localSystem.system` to each be updated by the other. But
this is not possible with the way the module system works. Divergence in
certain cases in inevitable.
This PR is more conservative and just has `system` default `localSystem`
and `localSystem` make the final call as-is. This solves a number of
issues.
- `localSystem` completely overrides `system`, just like with nixpkgs
proper. There is no need to specify `localSystem.system` to clobber the
old system.
- `config.nixpkgs.localSystem` is exactly what is passed to nixpkgs. No
spooky steps.
- `config.nixpkgs.localSystem` is elaborated just as nixpkgs would so
that all attributes are available, not just the ones the user
specified.
The remaining issue is just that `config.nixpkgs.system` doesn't update
based on `config.nixpkgs.localSystem.system`. It should never be
referred to lest it is a bogus stale value because
`config.nixpkgs.localSystem` overwrites it.
Fixes#46320
My c6f7d43678 made the mistake of not
having enough defaults. Now both variables are default as the *explicit*
value of the other, or a fallback. The fallback of `system` is the
default of `localSystem.system`. The fallback of `localSystem` is not
the other default (projected), as that would cause a cycle, but `{
system = builtins.currentTime; }` just as nixpkgs itself does it.
- `localSystem` is added, it strictly supercedes system
- `crossSystem`'s description mentions `localSystem` (and vice versa).
- No more weird special casing I don't even understand
TEMP
