--- a/dev-qt/qtcore/metadata.xml	
+++ a/dev-qt/qtcore/metadata.xml	
@@ -7,6 +7,7 @@ 
 	</maintainer>
 	<use>
 		<flag name="systemd">Enable native journald logging support</flag>
+		<flag name="ancient-kernel-support">Support kernels back to 2.6.28 (minimum is 3.17 otherwise)</flag>
 	</use>
 	<upstream>
 		<bugs-to>https://bugreports.qt.io/</bugs-to>
--- a/dev-qt/qtcore/qtcore-5.11.3-r2.ebuild	
+++ a/dev-qt/qtcore/qtcore-5.11.3-r2.ebuild	
@@ -11,7 +11,7 @@ if [[ ${QT5_BUILD_TYPE} == release ]]; then
 	KEYWORDS="amd64 ~arm ~arm64 ~hppa ~ppc ppc64 ~sparc x86 ~amd64-fbsd"
 fi
 
-IUSE="icu systemd"
+IUSE="ancient-kernel-support icu systemd"
 
 DEPEND="
 	dev-libs/double-conversion:=
@@ -57,6 +57,14 @@ src_configure() {
 		$(qt_use !icu iconv)
 		$(qt_use systemd journald)
 	)
+
+	if use ancient-kernel-support ; then
+		myconf+=(
+			-no-feature-getentropy  # needs 3.17
+			-no-feature-renameat2   # needs 3.16
+		)
+	fi
+
 	qt5-build_src_configure
 }