Merge `rust_main`. Change the way to pass multiboot info address.

kernel/src/arch/x86_64/boot/boot.asm

@@ -7,7 +7,7 @@ section .text
 bits 32
 start:
     mov esp, stack_top
-    mov edi, ebx       ; move Multiboot info pointer to edi
+    push ebx    ; push Multiboot info pointer to stack_top
 
     call check_multiboot
     call check_cpuid

kernel/src/arch/x86_64/mod.rs

@@ -11,9 +11,15 @@ pub mod idt;
 pub mod smp;
 pub mod memory;
 
-pub fn init(multiboot_information_address: usize) {
+pub fn init() {
     idt::init();
-    let boot_info = unsafe { multiboot2::load(multiboot_information_address) };
+    // Load boot info address from stack_top.
+    // See `boot.asm`
+    extern {
+        fn stack_top();
+    }
+    let boot_info_addr = unsafe { *(stack_top as *const u32).offset(-1) } as usize;
+    let boot_info = unsafe { multiboot2::load(boot_info_addr) };
     let rsdt_addr = boot_info.rsdp_v1_tag().unwrap().rsdt_address();
     memory::init(boot_info);
     // Now heap is available

kernel/src/lib.rs

@@ -76,32 +76,16 @@ mod arch;
 #[path = "arch/riscv32/mod.rs"]
 mod arch;
 
-#[no_mangle]
-#[cfg(target_arch = "riscv")]
-pub extern fn rust_main() -> ! {
-    logging::init();
-    arch::init();
-    info!("RISCV init end");
-    process::init();
-    fs::load_sfs();
-    unsafe { arch::interrupt::enable(); }
-    loop {}
-}
-
 /// The entry point of Rust kernel
 #[no_mangle]
-#[cfg(target_arch = "x86_64")]
-pub extern "C" fn rust_main(multiboot_information_address: usize) -> ! {
+pub extern "C" fn rust_main() -> ! {
     // ATTENTION: we have a very small stack and no guard page
     println!("Hello World{}", "!");
 
     logging::init();
-    arch::init(multiboot_information_address);
-
+    arch::init();
     process::init();
-
     fs::load_sfs();
-
     unsafe { arch::interrupt::enable(); }
 
 //    thread::test::local_key();