Print a “Hello World!” in Rust

.gitignore

@@ -1 +1,2 @@
 build
+target

Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "blog_os"
+version = "0.1.0"
+authors = ["Philipp Oppermann <dev@phil-opp.com>"]
+
+[lib]
+crate-type = ["staticlib"]
+
+[dependencies]
+rlibc = "1.0"

Makefile

@@ -1,6 +1,8 @@
 arch ?= x86_64
 kernel := build/kernel-$(arch).bin
 iso := build/os-$(arch).iso
+target ?= $(arch)-blog_os
+rust_os := target/$(target)/debug/libblog_os.a
 
 linker_script := src/arch/$(arch)/linker.ld
 grub_cfg := src/arch/$(arch)/grub.cfg
@@ -8,7 +10,7 @@ assembly_source_files := $(wildcard src/arch/$(arch)/*.asm)
 assembly_object_files := $(patsubst src/arch/$(arch)/%.asm, \
 	build/arch/$(arch)/%.o, $(assembly_source_files))
 
-.PHONY: all clean run iso
+.PHONY: all clean run iso kernel
 
 all: $(kernel)
 
@@ -27,8 +29,12 @@ $(iso): $(kernel) $(grub_cfg)
 	@grub-mkrescue -o $(iso) build/isofiles 2> /dev/null
 	@rm -r build/isofiles
 
-$(kernel): $(assembly_object_files) $(linker_script)
-	@ld -n -T $(linker_script) -o $(kernel) $(assembly_object_files)
+$(kernel): kernel $(rust_os) $(assembly_object_files) $(linker_script)
+	@ld -n --gc-sections -T $(linker_script) -o $(kernel) \
+		$(assembly_object_files) $(rust_os)
+
+kernel:
+	@xargo build --target $(target)
 
 # compile assembly files
 build/arch/$(arch)/%.o: src/arch/$(arch)/%.asm

README.md

@@ -1,12 +1,12 @@
-# Blog OS (Entering Longmode)
-[![Build Status](https://travis-ci.org/phil-opp/blog_os.svg?branch=post_2)](https://travis-ci.org/phil-opp/blog_os/branches)
+# Blog OS (Set Up Rust)
+[![Build Status](https://travis-ci.org/phil-opp/blog_os.svg?branch=post_3)](https://travis-ci.org/phil-opp/blog_os/branches)
 
-This repository contains the source code for the [Entering Longmode](http://os.phil-opp.com/entering-longmode.html) post of the [Writing an OS in Rust](http://os.phil-opp.com) series.
+This repository contains the source code for the [Set Up Rust](http://os.phil-opp.com/set-up-rust.html) post of the [Writing an OS in Rust](http://os.phil-opp.com) series.
 
 **Check out the [master branch](https://github.com/phil-opp/blog_os) for more information.**
 
 ## Building
-You need to have `nasm`, `grub-mkrescue`, `xorriso`, and `qemu` installed. Then you can run it using `make run`.
+You need to have `nasm`, `grub-mkrescue`, `xorriso`, `qemu`, and a nigthly Rust compiler installed. Then you can run it using `make run`.
 
 Please file an issue if you have any problems.
 

src/arch/x86_64/boot.asm

@@ -1,4 +1,5 @@
 global start
+extern long_mode_start
 
 section .text
 bits 32
@@ -12,6 +13,11 @@ start:
     call set_up_page_tables
     call enable_paging
 
+    ; load the 64-bit GDT
+    lgdt [gdt64.pointer]
+
+    jmp gdt64.code:long_mode_start
+
     ; print `OK` to screen
     mov dword [0xb8000], 0x2f4b2f4f
     hlt
@@ -147,3 +153,12 @@ p2_table:
 stack_bottom:
     resb 64
 stack_top:
+
+section .rodata
+gdt64:
+    dq 0 ; zero entry
+.code: equ $ - gdt64 ; new
+    dq (1<<43) | (1<<44) | (1<<47) | (1<<53) ; code segment
+.pointer:
+    dw $ - gdt64 - 1
+    dq gdt64

src/arch/x86_64/linker.ld

@@ -6,7 +6,7 @@ SECTIONS {
     .boot :
     {
         /* ensure that the multiboot header is at the beginning */
-        *(.multiboot_header)
+        KEEP(*(.multiboot_header))
     }
 
     .text :

src/arch/x86_64/long_mode_init.asm

@@ -0,0 +1,22 @@
+global long_mode_start
+extern rust_main
+
+section .text
+bits 64
+long_mode_start:
+    ; load 0 into all data segment registers
+    mov ax, 0
+    mov ss, ax
+    mov ds, ax
+    mov es, ax
+    mov fs, ax
+    mov gs, ax
+
+    ; call the rust main
+    extern rust_main
+    call rust_main
+
+    ; print `OKAY` to screen
+    mov rax, 0x2f592f412f4b2f4f
+    mov qword [0xb8000], rax
+    hlt

src/lib.rs

@@ -0,0 +1,26 @@
+#![feature(lang_items)]
+#![no_std]
+
+extern crate rlibc;
+
+#[no_mangle]
+pub extern fn rust_main() {
+    // ATTENTION: we have a very small stack and no guard page
+
+    let hello = b"Hello World!";
+    let color_byte = 0x1f; // white foreground, blue background
+
+    let mut hello_colored = [color_byte; 24];
+    for (i, char_byte) in hello.into_iter().enumerate() {
+        hello_colored[i*2] = *char_byte;
+    }
+
+    // write `Hello World!` to the center of the VGA text buffer
+    let buffer_ptr = (0xb8000 + 1988) as *mut _;
+    unsafe { *buffer_ptr = hello_colored };
+
+    loop{}
+}
+
+#[lang = "eh_personality"] extern fn eh_personality() {}
+#[lang = "panic_fmt"] #[no_mangle] pub extern fn panic_fmt() -> ! {loop{}}

x86_64-blog_os.json

@@ -0,0 +1,13 @@
+{
+  "llvm-target": "x86_64-unknown-none",
+  "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
+  "linker-flavor": "gcc",
+  "target-endian": "little",
+  "target-pointer-width": "64",
+  "target-c-int-width": "32",
+  "arch": "x86_64",
+  "os": "none",
+  "disable-redzone": true,
+  "features": "-mmx,-sse,+soft-float",
+  "panic-strategy": "abort"
+}