Add comment to config_psa.h about enabling PSA_HKDF/PSA_HKDF_EXRACT/PSA_HKDF_EXPAND algs
@@ -606,6 +606,10 @@ extern "C" {
#define PSA_WANT_ALG_GCM 1
#endif /* MBEDTLS_GCM_C */
+/* Enable PSA HKDF algorithm if mbedtls HKDF is supported.
+ * PSA HKDF EXTRACT and PSA HKDF EXPAND have minimal cost when
+ * PSA HKDF is enabled, so enable both algorithms together
+ * with PSA HKDF. */
#if defined(MBEDTLS_HKDF_C)
#define MBEDTLS_PSA_BUILTIN_ALG_HMAC 1
#define PSA_WANT_ALG_HMAC 1
