From 6013c37280fb0d52a41daa076d252d49b3c10a72 Mon Sep 17 00:00:00 2001
From: Hammarkvast <tomham-3@student.ltu.se>
Date: Wed, 8 Apr 2020 12:09:36 +0200
Subject: [PATCH] bare4_2
---
examples/bare4.rs | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/examples/bare4.rs b/examples/bare4.rs
index 839d1e8..6628884 100644
--- a/examples/bare4.rs
+++ b/examples/bare4.rs
@@ -36,8 +36,8 @@ use address::*;
#[inline(always)]
fn read_u32(addr: u32) -> u32 {
- unsafe { core::ptr::read_volatile(addr as *const _) }
- //core::ptr::read_volatile(addr as *const _)
+ //unsafe { core::ptr::read_volatile(addr as *const _) }
+ core::ptr::read_volatile(addr as *const _)
}
#[inline(always)]
@@ -104,12 +104,18 @@ fn main() -> ! {
// What was the error message and explain why.
//
// ** your answer here **
+// error[E0133]: call to unsafe function is unsafe and requires unsafe function or block
+// read_volatile is an unsafe function, which requires it to be called under a unsafe block.
//
// Digging a bit deeper, why do you think `read_volatile` is declared `unsafe`.
// (https://doc.rust-lang.org/core/ptr/fn.read_volatile.html, for some food for thought )
//
// ** your answer here **
//
+// read_volatile is inherently unsafe because reading a volatile variable is, indeed volatile
+// A volatile variable is volatile because it moves the value out of the address without
+// preventing further usage of that specific address.
+//
// Commit your answers (bare4_2)
//
// 3. Volatile read/writes are explicit *volatile operations* in Rust, while in C they
--
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