Introduce boot parameter root_trim=(yes|no) for SSDs

defaults/initrd.scripts

@@ -732,7 +732,7 @@ openLUKS() {
 			;;
 	esac
 
-	eval local LUKS_DEVICE='"${CRYPT_'${TYPE}'}"' LUKS_NAME="$1" LUKS_KEY='"${CRYPT_'${TYPE}'_KEY}"' LUKS_KEYDEV='"${CRYPT_'${TYPE}'_KEYDEV}"'
+	eval local LUKS_DEVICE='"${CRYPT_'${TYPE}'}"' LUKS_NAME="$1" LUKS_KEY='"${CRYPT_'${TYPE}'_KEY}"' LUKS_KEYDEV='"${CRYPT_'${TYPE}'_KEYDEV}"' LUKS_TRIM='"${CRYPT_'${TYPE}'_TRIM}"'
 	local DEV_ERROR=0 KEY_ERROR=0 KEYDEV_ERROR=0
 	local mntkey="/mnt/key/" cryptsetup_options=''
 
@@ -793,6 +793,12 @@ openLUKS() {
 				continue
 			else
 				# Handle keys
+				if [ "x${LUKS_TRIM}" = "xyes" ]
+				then
+					good_msg "Enabling TRIM support for ${LUKS_NAME}." ${CRYPT_SILENT}
+					cryptsetup_options="${cryptsetup_options} --allow-discards"
+				fi
+
 				if [ -n "${LUKS_KEY}" ] 
 				then
 					if [ ! -e "${mntkey}${LUKS_KEY}" ] 

defaults/linuxrc

@@ -189,6 +189,10 @@ do
 		root_keydev=*)
 			CRYPT_ROOT_KEYDEV=${x#*=}
 		;;
+		root_trim=*)
+			CRYPT_ROOT_TRIM=${x#*=}
+		;;
+
 		swap_key=*)
 			CRYPT_SWAP_KEY=${x#*=}
 		;;

doc/genkernel.8.txt

@@ -387,6 +387,11 @@ which the ramdisk scripts would recognize.
     root_key.   If unset while using root_key, it will automatically
     look for the device in every boot.
 
+*root_trim*=yes|no::
+    Allows you to enable TRIM support on root device. Only useful
+    for SSD setups. Have a look at http://en.wikipedia.org/wiki/TRIM
+    for more information.
+
 *swap_key*=<...>::
     Same as root_key for swap.