Previously, there was no way to unset an option when overriding a
kernel, apart from writing out the attrset yourself. Now it's
possible with lib.mkForce lib.kernel.unset. It's important to be able
to do this, because setting an option in the override may cause other
options to become unused, which would fail the config build unless
they were overridden too.
Remove the "version" parameter in order to make it more widely
available.
Starts making some kernel configuration helpers available.
The intent is to be able to better build and check the linux kernel
configuration.
This should make the composability of kernel configurations more straigthforward.
- now distinguish freeform options from tristate ones
- will look for a structured config in kernelPatches too
one can now access the structuredConfig from a kernel via linux_test.configfile.structuredConfig
in order to reinject it into another kernel, no need to rewrite the config from scratch
The following merge strategies are used in case of conflict:
-- freeform items must be equal or they conflict (mergeEqualOption)
-- for tristate (y/m/n) entries, I use the mergeAnswer strategy which takes the best available value, "best" being defined by the user (by default "y" > "m" > "n", e.g. if one entry is both marked "y" and "n", "y" wins)
-- if one item is both marked optional/mandatory, mandatory wins (mergeFalseByDefault)
Instead of using a string to describe kernel config, use a nix
attribute set, then converted to a string.
- allows to override the config, aka convert 'yes' into 'modules' or
vice-versa
- while for now merging different configs is still crude (last spec wins),
at least there should be only one CONFIG_XYZ value compared to the current string
config where the first defined would be used and others ignored.
[initial idea by copumpkin in 2016, a major rebase to 2018 by teto]
