[device] Add support 4.9 support for 7260CX3

files/Aboot/boot0.j2

@@ -170,6 +170,8 @@ platform_specific() {
         flash_size=28000
     fi
     if [ "$platform" = "rook" ]; then
+        echo "iommu=on intel_iommu=on tsc=reliable pcie_ports=native" >>/tmp/append
+        echo "rhash_entries=1 usb-storage.delay_use=0" >>/tmp/append
         if [ -x /bin/readprefdl ]; then
            readprefdl -f /tmp/.system-prefdl -d > /mnt/flash/.system-prefdl
         elif [ -f /etc/prefdl ]; then

files/initramfs-tools/arista-convertfs.j2

@@ -41,6 +41,9 @@ get_flash_dev() {
 wait_for_root_dev() {
     local try_rounds=30
     while [ $try_rounds -gt 0 ]; do
+        if blkid | sed 's/"//g' | grep -q "$root_dev"; then
+            return 0
+        fi
         if [ -e "$root_dev" ]; then
             return 0
         fi