"xz -9e" and "xz" size difference is very minimal:

$ du xz*/lib/modules/ -sk
42940   xz-e9/lib/modules/
42876   xz/lib/modules/

diff --git a/rpm.macros.kernel b/rpm.macros.kernel
index 3d24d00c473179ef9d65c76b9e2e5d787108cc6f..57aac808041c464c9e122202633484506f7e4691 100644 (file)
--- a/rpm.macros.kernel
+++ b/rpm.macros.kernel
@@ -97,6 +97,7 @@ done)
 # Supported values:
 # - "gzip -9nf" (module-init-tools and kmod)
 # - "xz" (kmod)
+# - "xz -9e" (kmod), however size difference with "xz" default options is very minimal
 # @since 1.707
 %kmod_compress_cmd %{__gzip} -9nf