nixpkgs/lib/kernel.nix

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{ lib
# we pass the kernel version here to keep a nice syntax `whenOlder "4.13"`
# kernelVersion, e.g., config.boot.kernelPackages.version
, version
, mkValuePreprocess ? null
}:
with lib;
rec {
# Common patterns
when = cond: opt: if cond then opt else null;
whenAtLeast = ver: when (versionAtLeast version ver);
whenOlder = ver: when (versionOlder version ver);
whenBetween = verLow: verHigh: when (versionAtLeast version verLow && versionOlder version verHigh);
# Keeping these around in case we decide to change this horrible implementation :)
option = x: if x == null then null else "?${x}";
yes = "y";
no = "n";
module = "m";
mkValue = val:
let
isNumber = c: elem c ["0" "1" "2" "3" "4" "5" "6" "7" "8" "9"];
in
if val == "" then "\"\""
else if val == yes || val == module || val == no then val
else if all isNumber (stringToCharacters val) then val
else if substring 0 2 val == "0x" then val
else val; # FIXME: fix quoting one day
# generate nix intermediate kernel config file of the form
#
# VIRTIO_MMIO m
# VIRTIO_BLK y
# VIRTIO_CONSOLE n
# NET_9P_VIRTIO? y
#
# Use mkValuePreprocess to preprocess option values, aka mark 'modules' as
# 'yes' or vice-versa
# Borrowed from copumpkin https://github.com/NixOS/nixpkgs/pull/12158
# returns a string, expr should be an attribute set
generateNixKConf = exprs: mkValuePreprocess:
let
mkConfigLine = key: rawval:
let
val = if builtins.isFunction mkValuePreprocess then mkValuePreprocess rawval else rawval;
in
if val == null
then ""
else if hasPrefix "?" val
then "${key}? ${mkValue (removePrefix "?" val)}\n"
else "${key} ${mkValue val}\n";
mkConf = cfg: concatStrings (mapAttrsToList mkConfigLine cfg);
in mkConf exprs;
}