From 7527d20d2533de1895857847d83f44b40c66861f Mon Sep 17 00:00:00 2001
From: Hsy-Intel <siyuan.hui@intel.com>
Date: Fri, 9 Aug 2024 18:35:41 +0800
Subject: [PATCH] Avoid generating Cmp_rm32_imm32 instruction

---
 ostd/src/bus/mmio/mod.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/ostd/src/bus/mmio/mod.rs b/ostd/src/bus/mmio/mod.rs
index 8518e8c72..80c4c57bf 100644
--- a/ostd/src/bus/mmio/mod.rs
+++ b/ostd/src/bus/mmio/mod.rs
@@ -63,8 +63,8 @@ fn iter_range(range: Range<usize>) {
     while current > range.start {
         current -= 0x100;
         // SAFETY: It only read the value and judge if the magic value fit 0x74726976
-        let value = unsafe { *(paddr_to_vaddr(current) as *const u32) };
-        if value == VIRTIO_MMIO_MAGIC {
+        let magic = unsafe { core::ptr::read_volatile(paddr_to_vaddr(current) as *const u32) };
+        if magic == VIRTIO_MMIO_MAGIC {
             // SAFETY: It only read the device id
             let device_id = unsafe { *(paddr_to_vaddr(current + 8) as *const u32) };
             device_count += 1;