Use _enter for program entrypoint instead of _start, and change entry to start

src/main.rs

@@ -11,7 +11,7 @@ mod uart;
 #[naked]
 #[no_mangle]
 #[link_section = ".text.init"]
-unsafe extern "C" fn _start() -> ! {
+unsafe extern "C" fn _enter() -> ! {
     use core::arch::asm;
     asm!(
         // before we use the `la` pseudo-instruction for the first time,
@@ -35,14 +35,14 @@ unsafe extern "C" fn _start() -> ! {
     "2:",
         // BSS is clear!
 
-        // "tail-call" to {entry} (call without saving a return address)
-        "tail {entry}",
-        entry = sym entry, // {entry} refers to the function [entry] below
+        // "tail-call" to {start} (call without saving a return address)
+        "tail {start}",
+        start = sym start, // {start} refers to the function [start] below
         options(noreturn) // we must handle "returning" from assembly
     );
 }
 
-extern "C" fn entry() -> ! {
+extern "C" fn start() -> ! {
     // UNSAFE: Called exactly once, right here.
     unsafe { heap::init() };
 

src/script.ld

@@ -1,7 +1,7 @@
 # src/script.ld
 
 OUTPUT_ARCH("riscv")
-ENTRY(_start)
+ENTRY(_enter)
 
 MEMORY {
   ram   (wxa) : ORIGIN = 0x80000000, LENGTH = 128M