diff --git a/tools/include/uapi/linux/bpf_common.h b/tools/include/uapi/linux/bpf_common.h
index 18be90725ab04a4a3fa2691d3eb57067778399d5..ee97668bdadb31585815e271af40667b6dea8b53 100644
--- a/tools/include/uapi/linux/bpf_common.h
+++ b/tools/include/uapi/linux/bpf_common.h
@@ -15,9 +15,10 @@
 
 /* ld/ldx fields */
 #define BPF_SIZE(code)  ((code) & 0x18)
-#define		BPF_W		0x00
-#define		BPF_H		0x08
-#define		BPF_B		0x10
+#define		BPF_W		0x00 /* 32-bit */
+#define		BPF_H		0x08 /* 16-bit */
+#define		BPF_B		0x10 /*  8-bit */
+/* eBPF		BPF_DW		0x18    64-bit */
 #define BPF_MODE(code)  ((code) & 0xe0)
 #define		BPF_IMM		0x00
 #define		BPF_ABS		0x20