Seed entropy using arm rng

src/arch/aarch64/kernel/processor.rs

@@ -1,6 +1,7 @@
 use core::arch::asm;
 use core::{fmt, mem};
 
+use aarch64_cpu::asm::random::ArmRng;
 use aarch64_cpu::registers::*;
 use hermit_sync::{Lazy, OnceCell, without_interrupts};
 
@@ -196,8 +197,16 @@ impl fmt::Display for CpuFrequency {
 	}
 }
 
+static RNG: Lazy<Option<ArmRng>> = Lazy::new(ArmRng::new);
+
 pub fn seed_entropy() -> Option<[u8; 32]> {
-	None
+	let rng = RNG.as_ref()?;
+	let mut buf = [0u8; 32];
+	for word in buf.chunks_mut(8) {
+		let value = rng.rndr().or(None).unwrap().to_ne_bytes();
+		word.copy_from_slice(&value);
+	}
+	Some(buf)
 }
 
 /// The halt function stops the processor until the next interrupt arrives