the kernel parameters has little modification for redhat 6 because of the dracut.

git-svn-id: https://svn.code.sf.net/p/xcat/code/xcat-core/trunk@6651 8638fb3e-16cb-4fca-ae20-7b5d299a9bcd

xCAT-server/lib/xcat/plugins/anaconda.pm

@@ -441,8 +441,13 @@ sub mknetboot
 			}
 		}
 
-		$kcmdline = 
-		"NFSROOT=$nfssrv:$nfsdir STATEMNT=";	
+        # special case for redhat6,
+        # TODO: fedora 12 and 13 also need it
+        if ($osver =~ m/rhel6/ || $osver =~ m/rhels6/) {
+            $kcmdline = "ip=dhcp root=nfs:$nfssrv:$nfsdir/rootimg:ro STATEMNT=";
+        } else {
+            $kcmdline = "NFSROOT=$nfssrv:$nfsdir STATEMNT=";	
+        }
 
         # add support for subVars in the value of "statemnt"
         my $statemnt = "";