mkefidisk: Always use rootwait and document kernel parameters used

Without a reliable way of knowing if the target device with be an
asyncronous block device on the target (MMC or USB), err on the side of
caution of always specifcy "rootwait", ensuring the kernel will wait for
the device to appear and not abort if it hasn't appeared in time for
mount.

Document the remaining kernel parameters added by this script on the
same line as rootwait.

Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

diff --git a/scripts/contrib/mkefidisk.sh b/scripts/contrib/mkefidisk.sh
index 9275ecf17c3da5fae2e8a19d7948cb651547d407..f8c08dd204ec7b8556e116c96349afd136c7f8af 100755 (executable)
--- a/scripts/contrib/mkefidisk.sh
+++ b/scripts/contrib/mkefidisk.sh
@@ -132,9 +132,7 @@ ROOTFS_START=$((BOOT_SIZE))
 ROOTFS_END=$((ROOTFS_START+ROOTFS_SIZE))
 SWAP_START=$((ROOTFS_END))
 
-# MMC devices are special in a couple of ways
-# 1) they use a partition prefix character 'p'
-# 2) they are detected asynchronously (need ROOTWAIT)
+# MMC devices use a partition prefix character 'p'
 PART_PREFIX=""
 if [ ! "${DEVICE#/dev/mmcblk}" = "${DEVICE}" ]; then
        PART_PREFIX="p"
@@ -143,11 +141,9 @@ BOOTFS=$DEVICE${PART_PREFIX}1
 ROOTFS=$DEVICE${PART_PREFIX}2
 SWAP=$DEVICE${PART_PREFIX}3
 
-ROOTWAIT=""
 TARGET_PART_PREFIX=""
 if [ ! "${TARGET_DEVICE#/dev/mmcblk}" = "${TARGET_DEVICE}" ]; then
        TARGET_PART_PREFIX="p"
-       ROOTWAIT="rootwait"
 fi
 TARGET_ROOTFS=$TARGET_DEVICE${TARGET_PART_PREFIX}2
 TARGET_SWAP=$TARGET_DEVICE${TARGET_PART_PREFIX}3
@@ -250,10 +246,14 @@ sed -i "/menuentry 'install'/,/^}/d" $GRUBCFG
 sed -i "/initrd /d" $GRUBCFG
 # Delete any LABEL= strings
 sed -i "s/ LABEL=[^ ]*/ /" $GRUBCFG
-# Replace the ramdisk root (if any) with the install device and include other
-# kernel parameters
+# Remove any existing root= kernel parameters and:
+# o Add a root= parameter with the target rootfs
+# o Specify ro so fsck can be run during boot
+# o Specify rootwait in case the target media is an asyncronous block device
+#   such as MMC or USB disks
+# o Specify "quiet" to minimize boot time when using slow serial consoles
 sed -i "s@ root=[^ ]*@ @" $GRUBCFG
-sed -i "s@vmlinuz @vmlinuz root=$TARGET_ROOTFS ro $ROOTWAIT quiet @" $GRUBCFG
+sed -i "s@vmlinuz @vmlinuz root=$TARGET_ROOTFS ro rootwait quiet @" $GRUBCFG
 
 # Provide a startup.nsh script for older firmware with non-standard boot
 # directories and paths.