--- qtcore-5.14.1-r1.ebuild	2020-03-22 22:09:47.427004415 +0800
+++ qtcore-5.14.1-r2.ebuild	2020-03-22 22:11:10.897208177 +0800
@@ -11,7 +11,7 @@
 	KEYWORDS="~amd64 ~arm ~arm64 ~hppa ~ppc ~ppc64 ~sparc ~x86"
 fi
 
-IUSE="icu systemd"
+IUSE="icu old-kernel systemd"
 
 DEPEND="
 	dev-libs/double-conversion:=
@@ -57,6 +57,8 @@
 src_configure() {
 	local myconf=(
 		-no-feature-statx	# bug 672856
+		$(qt_use !old-kernel feature-renameat2)  # needs Linux 3.16
+		$(qt_use !old-kernel feature-getentropy) # needs Linux 3.17
 		$(qt_use icu)
 		$(qt_use !icu iconv)
 		$(qt_use systemd journald)