runqemu - improve auto-detection of rootfs filenames

index 74938f7..8f44c0d 100755
@@ -241,31 +241,24 @@ machine2=`echo $MACHINE | tr 'a-z' 'A-Z' | sed 's/-/_/'`
 # Defaults used when these vars need to be inferred
 QEMUX86_DEFAULT_KERNEL=bzImage-qemux86.bin
 QEMUX86_DEFAULT_FSTYPE=ext3
-QEMUX86_DEFAULT_ROOTFS="core-image-sato-sdk core-image-sato core-image-lsb core-image-basic core-image-minimal"
 
 QEMUX86_64_DEFAULT_KERNEL=bzImage-qemux86-64.bin
 QEMUX86_64_DEFAULT_FSTYPE=ext3
-QEMUX86_64_DEFAULT_ROOTFS="core-image-sato-sdk core-image-sato core-image-lsb core-image-basic core-image-minimal"
 
 QEMUARM_DEFAULT_KERNEL=zImage-qemuarm.bin
 QEMUARM_DEFAULT_FSTYPE=ext3
-QEMUARM_DEFAULT_ROOTFS="core-image-sato-sdk core-image-sato core-image-lsb core-image-basic core-image-minimal"
 
 QEMUMIPS_DEFAULT_KERNEL=vmlinux-qemumips.bin
 QEMUMIPS_DEFAULT_FSTYPE=ext3
-QEMUMIPS_DEFAULT_ROOTFS="core-image-sato-sdk core-image-sato core-image-lsb core-image-basic core-image-minimal"
 
 QEMUPPC_DEFAULT_KERNEL=zImage-qemuppc.bin
 QEMUPPC_DEFAULT_FSTYPE=ext3
-QEMUPPC_DEFAULT_ROOTFS="core-image-sato-sdk core-image-sato core-image-lsb core-image-basic core-image-minimal"
 
 AKITA_DEFAULT_KERNEL=zImage-akita.bin
 AKITA_DEFAULT_FSTYPE=jffs2
-AKITA_DEFAULT_ROOTFS="core-image-sato"
 
 SPITZ_DEFAULT_KERNEL=zImage-spitz.bin
 SPITZ_DEFAULT_FSTYPE=ext3
-SPITZ_DEFAULT_ROOTFS="core-image-sato"
 
 setup_tmpdir() {
     if [ -z "$TMPDIR" ]; then

@@ -302,26 +295,28 @@ setup_sysroot() {
     fi 
 }
 
-# Locate a rootfs image based on defaults defined above
+# Locate a rootfs image to boot which matches our expected
+# machine and fstype. 
 findimage() {
     where=$1
     machine=$2
     extension=$3
-    names=$4
 
-    for name in $names; do
-        fullname=$where/$name-$machine.$extension
-        if [ -e "$fullname" ]; then
-            ROOTFS=$fullname
+    # Sort rootfs candidates by modification time - the most
+    # recently created one is the one we most likely want to boot.
+    filenames=`ls -t $where/*core-image*$machine.$extension 2>/dev/null | xargs`
+    for name in $filenames; do
+        if [[ "$name" =~ core-image-sato-sdk ||
+              "$name" =~ core-image-sato     ||
+              "$name" =~ core-image-lsb      ||
+              "$name" =~ core-image-basic    ||
+              "$name" =~ core-image-minimal ]]; then
+            ROOTFS=$name
             return
-        fi
-    done
-
-    echo "Couldn't find image in $where. Attempted image names were:"
-    for name in $names; do
-        echo $name-$machine.$extension
+        fi	
     done
 
+    echo "Couldn't find a $machine rootfs image in $where."
     exit 1
 }
 

@@ -378,7 +373,7 @@ if [ -z "$ROOTFS" ]; then
     setup_tmpdir
     T=$TMPDIR/deploy/images
     eval rootfs_list=\$${machine2}_DEFAULT_ROOTFS
-    findimage $T $MACHINE $FSTYPE "$rootfs_list"
+    findimage $T $MACHINE $FSTYPE
 
     if [ -z "$ROOTFS" ]; then
         echo "Error: Unable to determine default rootfs for MACHINE [$MACHINE]"