anchor.diff:  
     # set CHROME_PLATFORMS flag; needed for touchpad.
     # note: this means nix will need to build linux. fun!
  -  nixpkgs.config = {
  -    packageOverrides = super: let self = super.pkgs; in rec {
  -      stdenv = super.stdenv // {
  -        platform = super.stdenv.platform // {
  -          kernelExtraConfig = ''
  -            CHROME_PLATFORMS y
  -          '';
  -        };
  -      };
  -    };
  -  };
  +  # nixpkgs.config = {
  +  #   packageOverrides = super: let self = super.pkgs; in rec {
  +  #     stdenv = super.stdenv // {
  +  #       platform = super.stdenv.platform // {
  +  #         kernelExtraConfig = ''
  +  #           CHROME_PLATFORMS y
  +  #         '';
  +  #       };
  +  #     };
  +  #   };
  +  # };
   
     # maybe this is needed?
     services.xserver.vaapiDrivers = [ pkgs.vaapiIntel ];
  
positive.code: # Acer C720-specific configuration.
  #
  # Unfortunately things are not working quite yet. Suspend/resume
  # causes some sort of weird USB error to fill up the system logs, and
  # I have to force shut the computer down. I am hopefull I'll get it
  # working eventually, apparently it has been done.
  #
  # The trackpad works, but is -- touchy. If I brush it at all, it
  # clicks or does something silly. I have to build the kernel with a
  # custom flag set for it to work at all.
  #
  # I would like the power button not to immediately shut the computer
  # down without any warning when I am, say, working in emacs and trying
  # to hit the backspace key. (Perhaps this is an xmonad config thing.)
  
  { config, pkgs, ...}:
  
  {
  
    # Asus C720 suspend compat -- doesn't seem to work.
    boot.blacklistedKernelModules = [ "ehci_pci" ];
    boot.kernelParams = [
      "tpm_tis.interrupts=0"
      "i915.enable_ips=0"
    ];
  
    # Get sound working.
    # (disable the first intel sound card, enable the second.)
  
negative.code:     options snd_hda_intel enable=0,1
    '';
  
    boot.cleanTmpDir = true;
    powerManagement.enable = true;
    powerManagement.cpuFreqGovernor = "conservative";
  
    hardware.cpu.intel.updateMicrocode = true;
  
    # Use power key as a suspend key. More useful (and safe) than power
    # off, b/c I hit it by accident a lot.
    services.logind.extraConfig = ''
      HandlePowerKey=suspend
      HandleLidSwitch=suspend
    '';
  
    # Touchpad configuration.
    services.xserver.synaptics = {
  