diff --git a/gcc/config/aarch64/aarch64-cores.def b/gcc/config/aarch64/aarch64-cores.def
index 2a0f52e1dd93ad1fa42bdb6a8654c731c4028f2b..e014dc84074bb5f8d2e2f77b36f19dbd8d6998a4 100644
--- a/gcc/config/aarch64/aarch64-cores.def
+++ b/gcc/config/aarch64/aarch64-cores.def
@@ -29,7 +29,10 @@
    will be made, represented as an identifier.
    ARCH_IDENT is the architecture implemented by the chip as specified in
    aarch64-arches.def.
-   FLAGS are the bitwise-or of the traits that apply to that core.
+   FLAGS is a parentheses-enclosed, comma-separated list of architecture
+   features in the core that are present in addition to the base architecture.
+   The architecture feature names are as per the identifiers in
+   aarch64-option-extensions.def.
    This need not include flags implied by the architecture.
    COSTS is the name of the rtx_costs routine to use.
    IMP is the implementer ID of the CPU vendor.  On a GNU/Linux system it