dd-multi.sh: change partitioning procedure

Initially write 10MB of 0's instead of 1MB to make sure any tables
at the beginning are really gone.

Rather than calling 'partprobe' with no arguments, explicitly pass
the list of devices to re-read.

'fdisk' is used to create the 2nd (/home) partition. Do not do that
in the background but instead synchronously for each device. Add a
'sync' afterwards to hopefully create a barrier before rescanning
the devices. This is should address a problem where 'partprobe' is
run too early and the kernel does not find the 2nd partition of the
last device.

Signed-off-by: John Ogness <john.ogness@linutronix.de>

1 files changed, 27 insertions, 36 deletions

diff --git a/lx-trainer-vm/dd-multi.sh b/lx-trainer-vm/dd-multi.sh
index 2af3798..998aaf5 100755
--- a/lx-trainer-vm/dd-multi.sh
+++ b/lx-trainer-vm/dd-multi.sh
@@ -6,14 +6,14 @@ usage_exit()
 	echo
 	echo "usage: $0 src [--layer=tarball]... dest [dest]..."
 	echo
-	echo "example: copying image to devs sde, sdf, sdg"
+	echo "example: copying image to devices: sde, sdf, sdg"
 	echo "$0 lx-trainer.img /dev/sde /dev/sdf /dev/sdg"
 	echo
 	exit 1
 }
 
 if [ `id -u` -ne 0 ]; then
-	echo "error: this script must be run as root"
+	echo "error: sorry, this script must be run as root"
 	exit 1
 fi
 
@@ -29,22 +29,22 @@ LAYERS=""
 DESTS=""
 
 for arg in $@; do
-case $arg in
---layer=*)
-	LAYERS="$LAYERS `echo $arg | sed -e 's/^--layer=//'`"
-	;;
---*)
-	echo "error: unknown option: $arg"
-	usage_exit
-	;;
-*)
-	if [ -z "$SRC" ]; then
-		SRC="$arg"
-	else
-		DESTS="$DESTS $arg"
-	fi
-	;;
-esac
+	case $arg in
+	--layer=*)
+		LAYERS="$LAYERS `echo $arg | sed -e 's/^--layer=//'`"
+		;;
+	--*)
+		echo "error: unknown option: $arg"
+		usage_exit
+		;;
+	*)
+		if [ -z "$SRC" ]; then
+			SRC="$arg"
+		else
+			DESTS="$DESTS $arg"
+		fi
+		;;
+	esac
 done
 
 # source must be file or block device
@@ -61,31 +61,22 @@ for dest in $DESTS; do
 	fi
 done
 
-# check if we are root (but keep going)
-if [ `id -u` -ne 0 ]; then
-	echo "warning: not root, may not work"
-fi
+# delete mbr's and rescan devices
+dd if=/dev/zero bs=1M count=10 | tee $DESTS > /dev/null
+partprobe $DESTS
 
-# delete mbr
-for dest in $DESTS; do
-	dd if=/dev/zero of=$dest bs=1M count=1 &
-done
-wait
-
-partprobe
-
-# efficiently copy source to all destinations
+# efficiently copy source to all destinations and rescan devices
 cat $SRC | tee $DESTS > /dev/null
-
-partprobe
+partprobe $DESTS
 
 # add 2nd partition
 for dest in $DESTS; do
-	/bin/echo -e "n\np\n\n\n\nw" | fdisk $dest &
+	/bin/echo -e "n\np\n\n\n\nw" | fdisk $dest
 done
-wait
+sync
 
-partprobe
+# rescan devices
+partprobe $DESTS
 
 # create ext4 on 2nd partition
 for dest in $DESTS; do