smem -s swap -kta
smem --sort swap --abbreviate --totals --autosize

swap     (amount of swap space consumed ignoring sharing)
command  (process command line)
maps     (total mappings count)
name     (process name)
pid      (process id #)
user     (process owner)
pss      (proportional set size including sharing)
rss      (resident set size ignoring sharing)
uss      (unique set size)
vss      (virtual set size; total virtual memory mapped)

df -h | grep tmpfs
df --human-readable | grep tmpfs

$ readlink --canonicalize "$(type -P which)"
/nix/store/r78jv9xgxnvsm5vpasf5ldkc28pkri6r-which-2.21/bin/which

$ nix-store --query --references /nix/store/r78jv9xgxnvsm5vpasf5ldkc28pkri6r-which-2.21
/nix/store/4nlgxhb09sdr51nc9hdm8az5b08vzkgx-glibc-2.35-163

guix graph --type=references which

{ stdenv, lib, fetchgit, linuxKernel, kernel ? linuxKernel.kernels.linux_5_15
, version ? "d0d785dc1859b09299bde6d0f1d6786a0d610e7f" }:

stdenv.mkDerivation {

  inherit version;
  name = "sna-hda-codec-cs8409-${version}-module-${kernel.modDirVersion}";

  # Upstream: https://github.com/davidjo/snd_hda_macbookpro

  src = fetchgit {
    url = "https://github.com/egorenar/snd-hda-codec-cs8409.git";
    rev = version;
    sha256 = "sha256-0UeoERcYpM+ojeZ7dDIE3ruTIoHkkC+s7FcoEVUTR0w=";
  };

  hardeningDisable = [ "pic" ];
  nativeBuildInputs = kernel.moduleBuildDependencies;

  NIX_CFLAGS_COMPILE = [ "-g" "-Wall" "-Wno-unused-variable" "-Wno-unused-function" ];

  makeFlags = kernel.makeFlags ++ [
    "INSTALL_MOD_PATH=$(out)"
    "KERNELRELEASE=${kernel.modDirVersion}"
    "KERNEL_DIR=${kernel.dev}/lib/modules/${kernel.modDirVersion}/build"
  ];

  postPatch = ''
    printf '
    snd-hda-codec-cs8409-objs := patch_cs8409.o patch_cs8409-tables.o
    obj-$(CONFIG_SND_HDA_CODEC_CS8409) += snd-hda-codec-cs8409.o

    KBUILD_EXTRA_CFLAGS = "-DAPPLE_PINSENSE_FIXUP -DAPPLE_CODECS -DCONFIG_SND_HDA_RECONFIG=1"

    KERNELRELEASE ?= $(shell uname -r)
    KERNEL_DIR    ?= /lib/modules/$(KERNELRELEASE)/build
    PWD           := $(shell pwd)

    default:
    	make -C $(KERNEL_DIR) M=$(PWD) CFLAGS_MODULE=$(KBUILD_EXTRA_CFLAGS)

    install:
    	make -C $(KERNEL_DIR) M=$(PWD) modules_install
    ' \
    > Makefile

    sed --in-place 's|<sound/cs42l42.h>|"${linuxKernel.kernels.linux_6_0.dev}/lib/modules/${linuxKernel.kernels.linux_6_0.modDirVersion}/source/include/sound/cs42l42.h"|'  patch_cs8409.h
    sed --in-place 's|hda_local.h|${kernel.dev}/lib/modules/${kernel.modDirVersion}/source/sound/pci/hda/hda_local.h|'                                                      patch_cs8409.h
    sed --in-place 's|hda_jack.h|${kernel.dev}/lib/modules/${kernel.modDirVersion}/source/sound/pci/hda/hda_jack.h|'                                                        patch_cs8409.h
    sed --in-place 's|hda_generic.h|${kernel.dev}/lib/modules/${kernel.modDirVersion}/source/sound/pci/hda/hda_generic.h|'                                                  patch_cs8409.h
    sed --in-place 's|hda_auto_parser.h|${kernel.dev}/lib/modules/${kernel.modDirVersion}/source/sound/pci/hda/hda_auto_parser.h|'                                          patch_cs8409.h
  '';

  meta = { platforms = lib.platforms.linux; };
}

{ pkgs, ... }:

{
  boot = {
    extraModulePackages = [
      (pkgs.callPackage ../packages/snd-hda-cs8409/default.nix {
        kernel = pkgs.linux_5_15;
      })
    ];
  };
}

{ config, ... }:

{
  nix = {
    package = (import ../versions.nix).nix_2_17 { inherit config; };
    settings = {
      log-lines = 25;                                # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-log-lines
      fallback = true;                               # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-fallback
      tarball-ttl = 0;                               # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-tarball-ttl
      show-trace = true;                             # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-show-trace
      connect-timeout = 5;                           # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-connect-timeout
      auto-optimise-store = true;                    # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-auto-optimise-store
      narinfo-cache-negative-ttl = 0;                # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-narinfo-cache-negative-ttl
      narinfo-cache-positive-ttl = 0;                # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-narinfo-cache-positive-ttl
      builders-use-substitutes = true;               # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-builders-use-substitutes
      min-free = 268435456;                          # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-min-free (256 MB in Bytes)
      max-free = 1073741824;                         # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-max-free (1 GB in Bytes)
      allowed-users = [ "root" "@wheel" ];           # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-allowed-users
      trusted-users = [ "root" "@wheel" ];           # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-trusted-users
      experimental-features = "nix-command flakes";  # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-experimental-features
    };
  };
}