make root=dhcp work

modules.d/40network/ifup

@@ -93,8 +93,14 @@ ip_to_var() {
     [ -n "$autoconf" ] || autoconf=off
 }
 
-# spin through the kernel command line, looking for ip= lines
-for p in $(cat /proc/cmdline); do
+root=$(getarg root)
+ip=$(getarg ip)
+
+if [ "$root" = "dhcp" -a -z "$ip" ]; then
+    do_dhcp;
+else
+    # spin through the kernel command line, looking for ip= lines
+    for p in $(cat /proc/cmdline); do
 	[ -n "${p%ip=*}" ] && continue
 	ip_to_var ${p#ip=}
 	
@@ -108,5 +114,6 @@ for p in $(cat /proc/cmdline); do
 	    ''|none|off)	 ;;
 	esac
 	break
-done
+    done
+fi
 exit 0