* ALSA support: save/restore the volume settings, create device nodes

in /dev/snd.

svn path=/nixos/trunk/; revision=8124

system/options.nix

@@ -749,4 +749,13 @@
   }
 
   
+  {
+    name = ["sound" "enable"];
+    default = true;
+    description = "
+      Whether to enable ALSA sound.
+    ";
+  }
+
+  
 ]

system/system.nix

@@ -197,7 +197,8 @@ rec {
     nixosRebuild
     nixosCheckout
     setuidWrapper
-  ];
+  ]
+  ++ (if config.get ["sound" "enable"] then [pkgs.alsaUtils] else []);
 
 
   # We don't want to put all of `startPath' and `path' in $PATH, since

system/upstart.nix

@@ -131,6 +131,12 @@ import ../upstart-jobs/gather.nix {
       inherit (pkgs) glibc pwdutils;
     })
 
+  # ALSA sound support.
+  ++ optional ["sound" "enable"]
+    (import ../upstart-jobs/alsa.nix {
+      inherit (pkgs) kernel module_init_tools alsaUtils;
+    })
+
   # Handles the reboot/halt events.
   ++ (map
     (event: makeJob (import ../upstart-jobs/halt.nix {

upstart-jobs/alsa.nix

@@ -0,0 +1,38 @@
+{kernel, module_init_tools, alsaUtils}:
+
+let
+
+  soundState = "/var/state/asound.state";
+
+in
+  
+{
+  name = "alsa";
+  
+  job = "
+start on hardware-scan
+stop on shutdown
+
+script
+
+    # Load some additional modules.
+    export MODULE_DIR=${kernel}/lib/modules/
+    for mod in snd_pcm_oss; do
+        ${module_init_tools}/sbin/modprobe $mod || true
+    done
+
+    # Restore the sound state.
+    ${alsaUtils}/sbin/alsactl -f ${soundState} restore
+
+end script
+
+stop script
+
+    # Save the sound state.
+    ${alsaUtils}/sbin/alsactl -f ${soundState} store
+
+end script
+
+  ";
+
+}

upstart-jobs/udev-rules/50-udev.rules

@@ -28,3 +28,12 @@ KERNEL=="uinput",               NAME="input/%k", MODE="0600"
 
 # Create a symlink for the CD-ROM device.
 KERNEL=="hd[a-z]", BUS=="ide", SYSFS{removable}=="1", SYSFS{device/media}=="cdrom", SYMLINK+="cdrom cdrom-%k"
+
+
+# ALSA sound devices.
+KERNEL=="controlC[0-9]*",       NAME="snd/%k"
+KERNEL=="hwC[D0-9]*",           NAME="snd/%k"
+KERNEL=="pcmC[D0-9cp]*",        NAME="snd/%k"
+KERNEL=="midiC[D0-9]*",         NAME="snd/%k"
+KERNEL=="timer",                NAME="snd/%k"
+KERNEL=="seq",                  NAME="snd/%k"