Auto exit in qemu

Cargo.toml

@@ -6,6 +6,9 @@ authors = ["Philipp Oppermann <dev@phil-opp.com>"]
 [lib]
 crate-type = ["staticlib"]
 
+[features]
+qemu_auto_exit = []
+
 [dependencies]
 bit_field = "0.7.0"
 rlibc = "1.0"

Makefile

@@ -10,6 +10,10 @@ grub_cfg := $(boot_src)/grub.cfg
 assembly_source_files := $(wildcard $(boot_src)/*.asm)
 assembly_object_files := $(patsubst $(boot_src)/%.asm, \
 	build/arch/$(arch)/boot/%.o, $(assembly_source_files))
+qemu_opts := -cdrom $(iso) \
+			 -smp 2 \
+			 -device isa-debug-exit # enable shutdown inside the qemu 
+features := qemu_auto_exit
 
 ifeq ($(shell uname), Linux)
 	prefix :=
@@ -27,7 +31,7 @@ clean:
 	@rm -r build
 
 run: $(iso)
-	@qemu-system-$(arch) -cdrom $(iso) -smp 2
+	@qemu-system-$(arch) $(qemu_opts)
 
 iso: $(iso)
 
@@ -43,7 +47,7 @@ $(kernel): kernel $(rust_os) $(assembly_object_files) $(linker_script)
 		$(assembly_object_files) $(rust_os)
 
 kernel:
-	@RUST_TARGET_PATH=$(shell pwd) xargo build --target $(target)
+	@RUST_TARGET_PATH=$(shell pwd) xargo build --target $(target) --features $(features)
 
 # compile assembly files
 build/arch/$(arch)/boot/%.o: $(boot_src)/%.asm

src/arch/x86_64/cpu.rs

@@ -1,4 +1,4 @@
-// Enable 'No-Execute' bit in page entry
+/// Enable 'No-Execute' bit in page entry
 pub fn enable_nxe_bit() {
     use x86_64::registers::msr::{IA32_EFER, rdmsr, wrmsr};
 
@@ -11,11 +11,22 @@ pub fn enable_nxe_bit() {
     }
 }
 
-// Enable write protection in kernel mode
+/// Enable write protection in kernel mode
 pub fn enable_write_protect_bit() {
     use x86_64::registers::control_regs::{cr0, cr0_write, Cr0};
 
     // The CR0 register is only allowed in kernel mode
     // But we are in kernel mode. So it's safe.
     unsafe { cr0_write(cr0() | Cr0::WRITE_PROTECT) };
+}
+
+/// Exit qemu
+/// See: https://wiki.osdev.org/Shutdown
+/// Must run qemu with `-device isa-debug-exit`
+/// The error code is `value written to 0x501` *2 +1, so it should be odd
+pub unsafe fn exit_in_qemu(error_code: u8) -> ! {
+    use x86_64::instructions::port::outb;
+    assert!(error_code & 1 == 1);
+    outb(0x501, (error_code - 1) / 2);
+    unreachable!()
 }

src/arch/x86_64/mod.rs

@@ -1,5 +1,5 @@
 pub mod driver;
-mod cpu;
+pub mod cpu;
 
 pub fn init() {
 	cpu::enable_nxe_bit();

src/lang.rs

@@ -1,6 +1,7 @@
 // Rust language features implementions
 
 use core;
+use arch::cpu;
 
 #[lang = "eh_personality"] 
 extern fn eh_personality() {
@@ -11,5 +12,9 @@ extern fn eh_personality() {
 pub extern fn panic_fmt(fmt: core::fmt::Arguments, file: &'static str, line: u32) -> ! {
     println!("\n\nPANIC in {} at line {}:", file, line);
     println!("    {}", fmt);
-    loop{}
-}
+    if cfg!(feature = "qemu_auto_exit") {
+        unsafe{ cpu::exit_in_qemu(1) }
+    } else {
+        loop { }
+    }
+}