diff -ur xen-tools.orig//xen-tools-3.4.2-r5.ebuild xen-tools//xen-tools-3.4.2-r5.ebuild
--- xen-tools.orig//xen-tools-3.4.2-r5.ebuild	2011-10-04 18:47:04.179000378 +0800
+++ xen-tools//xen-tools-3.4.2-r5.ebuild	2011-10-04 19:23:23.220606115 +0800
@@ -76,6 +76,10 @@
 	usr/share/xen/qemu/openbios-sparc64"
 
 pkg_setup() {
+	if [ -x /.config/ ]; then
+		die "the system has a dir /.config; this needs to be removed to allow the package to emerge"
+	fi
+
 	export "CONFIG_LOMOUNT=y"
 
 	if ! use x86 && ! has x86 $(get_all_abis) && use hvm; then