anchor.diff:  
   let
   
  -  inherit (super) lib callPackage linuxPackagesFor;
  +  inherit (super) lib callPackage linuxPackagesFor recurseIntoAttrs;
  +
  +  # Since 20.09 this is a part of lib.kernel
  +  option = x:
  +      x // { optional = true; };
  +
  +  yes      = { tristate    = "y"; optional = false; };
  +  no       = { tristate    = "n"; optional = false; };
  +  module   = { tristate    = "m"; optional = false; };
  +  freeform = x: { freeform = x; optional = false; };
  +
  +  whenHelpers = version: with lib; {
  +    whenAtLeast = ver: mkIf (versionAtLeast version ver);
  +    whenOlder   = ver: mkIf (versionOlder version ver);
  +    # range is (inclusive, exclusive)
  +    whenBetween = verLow: verHigh: mkIf (versionAtLeast version verLow && versionOlder version verHigh);
  +  };
   
     cfg = super.config.musnix or {
       kernel.latencytop = false;
  
positive.code:     enableLatencytop ? cfg.kernel.latencytop,
      enableOptimization ? cfg.kernel.optimize
    }:
      with (lib.kernel);
      with (lib.kernel.whenHelpers version);
      lib.optionalAttrs enableLatencytop {
        LATENCYTOP = yes;
        SCHEDSTATS = yes;
  
negative.code:     };
  
    realtimeConfig = { version, enableLatencytop, enableOptimization }:
      with (whenHelpers version);
      (standardConfig { inherit version enableLatencytop enableOptimization; }) // {
        PREEMPT = whenOlder "5.4" yes; # PREEMPT_RT deselects it.
        PREEMPT_RT_FULL = whenOlder "5.4" yes; # Renamed to PREEMPT_RT when merged into the mainline.
  