cargo fmt and use core::compile_error

build.rs

@@ -1,12 +1,13 @@
 #[cfg(not(feature = "binary"))]
-#[allow(unreachable_code)]
 fn main() {
-    #[cfg(target_arch = "x86")]
-    panic!("This crate currently does not support 32-bit protected mode. \
-    See https://github.com/rust-osdev/bootloader/issues/70 for more information.");
+    //#[cfg(target_arch = "x86")]
+    compile_error!(
+        "This crate currently does not support 32-bit protected mode. \
+         See https://github.com/rust-osdev/bootloader/issues/70 for more information."
+    );
 
-    #[cfg(not(target_arch = "x86_64"))]
-    panic!("This crate only supports the x86_64 architecture.");
+    #[cfg(not(any(target_arch = "x86_64", target_arch = "x86")))]
+    compile_error!("This crate only supports the x86_64 architecture.");
 }
 
 #[cfg(feature = "binary")]

src/main.rs

@@ -25,7 +25,7 @@ use x86_64::ux::u9;
 use x86_64::{PhysAddr, VirtAddr};
 
 // The bootloader_config.rs file contains some configuration constants set by the build script:
-// PHYSICAL_MEMORY_OFFSET: The offset into the virtual address space where the physical memory 
+// PHYSICAL_MEMORY_OFFSET: The offset into the virtual address space where the physical memory
 // is mapped if the `map_physical_memory` feature is activated.
 //
 // KERNEL_STACK_ADDRESS: The virtual address of the kernel stack.