diff --git a/vmbase/src/hvc.rs b/vmbase/src/hvc.rs
index 9a5e716..4d489d5 100644
--- a/vmbase/src/hvc.rs
+++ b/vmbase/src/hvc.rs
@@ -22,13 +22,12 @@
 };
 
 const ARM_SMCCC_TRNG_VERSION: u32 = 0x8400_0050;
-#[allow(dead_code)]
 const ARM_SMCCC_TRNG_FEATURES: u32 = 0x8400_0051;
 #[allow(dead_code)]
 const ARM_SMCCC_TRNG_GET_UUID: u32 = 0x8400_0052;
 #[allow(dead_code)]
 const ARM_SMCCC_TRNG_RND32: u32 = 0x8400_0053;
-const ARM_SMCCC_TRNG_RND64: u32 = 0xc400_0053;
+pub const ARM_SMCCC_TRNG_RND64: u32 = 0xc400_0053;
 
 /// Returns the (major, minor) version tuple, as defined by the SMCCC TRNG.
 pub fn trng_version() -> trng::Result<(u16, u16)> {
@@ -49,3 +48,10 @@
 
     Ok((regs[1], regs[2], regs[3]))
 }
+
+pub fn trng_features(fid: u32) -> trng::Result<u64> {
+    let mut args = [0u64; 17];
+    args[0] = fid as u64;
+
+    positive_or_error_64::<Error>(hvc64(ARM_SMCCC_TRNG_FEATURES, args)[0])
+}