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
Intuitively, one cares mainly about the host platform: Platforms differ
in meaningful ways but compilation is morally a pure process and
probably doesn't care, or those difference are already abstracted away.
@Dezgeg also empirically confirmed that > 95% of checks are indeed of
the host platform.
Yet these attributes in the old cross infrastructure were defined to be
the build platform, for expediency. And this was never before changed.
(For native builds build and host coincide, so it isn't clear what the
intention was.)
Fixing this doesn't affect native builds, since again they coincide. It
also doesn't affect cross builds of anything in Nixpkgs, as these are no
longer used. It could affect external cross builds, but I deem that
unlikely as anyone thinking about cross would use more explicit
attributes for clarity, all the more so because the rarity of inspecting
the build platform.
I don't know when we can/should remove them, but this at least gets
people to stop using them. The preferred alternatives also date back to
17.09 so writing forward-compatable code without extra conditions is
easy.
Beginning with these as they are the least controversial.
Derivations where drawing their `system` attribute from `hostPlatform`
instead of `buildPlatform`. Fix that, and add an explanatory commment.
Fixes #45993
This, apparently, is not an official release (it's tagged, but the tarball is not
available on the official site), but this repo is the official repo mentioned on
the official site.
This fixes a bunch of very annoying bugs present in 0.99.4, e.g.
```
$ FBReader filename
```
does not crash anymore. Yay!
Although double '/' in paths is not a problem for GRUB supplied with nixpkgs, sometimes NixOS's grub.conf read by external GRUB and there are versions of GRUB which fail
Generated reverse path filtering rules for the macvlan interface
seem to be incorrect, causing the test to fail - sometimes or always,
depending on the dhcpcd version used.
- Disable reverse path checking temporarily to avoid blocking the channel
- Print more diagnostic information for debugging
The switch from slim to lightdm in #30890 broke some nixos tests
because lightdm by default doesn't permit auto-login for root.
Override /etc/pam.d/lightdm-autologin to allow it.
