[x86] sysupgrade: Get target device from kernel cmdline, patch from acinonyx

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@20538 3c298f89-4303-0410-b956-a3cf2f4a3e73

target/linux/x86/base-files/lib/upgrade/platform.sh

@@ -13,8 +13,12 @@ platform_check_image() {
 }
 
 platform_do_upgrade() {
+	local ROOTFS
 	sync
-	get_image "$1" > /dev/sda
+	grep -q -e "jffs2" -e "squashfs" /proc/cmdline \
+		&& ROOTFS="$(awk 'BEGIN { RS=" "; FS="="; } ($1 == "block2mtd.block2mtd") { print substr($2,1,index($2, ",")-1) }' < /proc/cmdline)" \
+		|| ROOTFS="$(awk 'BEGIN { RS=" "; FS="="; } ($1 == "root") { print $2 ) }' < /proc/cmdline)"
+	[ -b ${ROOTFS%[0-9]} ] && get_image "$1" > ${ROOTFS%[0-9]}
 }
 
 x86_prepare_ext2() {