WIP: convert to rust

.cargo/config

+[build]
+rustflags = [
+  # Kernel should preserve floating-point registers
+  "-Csoft-float",
+]
+
+[unstable]
+build-std = ["core", "alloc", "compiler_builtins"]
+build-std-features = ["panic-unwind"]

.gitignore

+/build
+/target

Cargo.lock

+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "redox_bootloader"
+version = "0.1.0"

Cargo.toml

+[package]
+name = "redox_bootloader"
+version = "0.1.0"
+edition = "2018"
+
+[lib]
+name = "bootloader"
+path = "src/lib.rs"
+crate-type = ["staticlib"]
+
+[dependencies]

Makefile

+ARCH=x86
+TARGET=$(ARCH)-unknown-none
+
+export LD=ld -m elf_i386
+export OBJCOPY=objcopy
+export PARTED=parted
+export QEMU=qemu-system-i386
+export RUST_TARGET_PATH=$(CURDIR)/targets
+
+all: build/bootloader.bin
+
+clean:
+	rm -rf build
+
+build/libbootloader.a: Cargo.lock Cargo.toml src/**
+	mkdir -p build
+	cargo rustc --lib --target $(TARGET) --release -- -C soft-float -C debuginfo=2 --emit link=$@
+
+build/bootloader.elf: linkers/$(ARCH).ld build/libbootloader.a
+	mkdir -p build
+	$(LD) --gc-sections -z max-page-size=0x1000 -T $< -o $@ build/libbootloader.a && \
+	$(OBJCOPY) --only-keep-debug $@ $@.sym && \
+	$(OBJCOPY) --strip-debug $@
+
+build/bootloader.bin: build/bootloader.elf $(ARCH)/**
+	mkdir -p build
+	nasm -f bin -o $@ -l $@.lst -D ARCH_$(ARCH) -D KERNEL=$< -i$(ARCH) $(ARCH)/disk.asm
+
+build/harddrive.bin: build/bootloader.bin
+	mkdir -p build
+	rm -f $@.partial
+	fallocate -l 256MiB $@.partial
+	$(PARTED) -s -a minimal $@.partial mklabel msdos
+	$(PARTED) -s -a minimal $@.partial mkpart primary 1MiB 100%
+	dd if=$< of=$@.partial bs=1 count=446 conv=notrunc
+	dd if=$< of=$@.partial bs=512 skip=1 seek=1 conv=notrunc
+	mv $@.partial $@
+
+qemu: build/harddrive.bin
+	$(QEMU) \
+		-d cpu_reset \
+		-d guest_errors \
+		-smp 4 -m 2048 \
+		-chardev stdio,id=debug,signal=off,mux=on \
+		-serial chardev:debug \
+		-mon chardev=debug \
+		-machine q35 \
+		-net none \
+		-enable-kvm \
+		-cpu host \
+		-drive file=$<,format=raw

linkers/x86.ld

+ENTRY(kstart)
+OUTPUT_FORMAT(elf32-i386)
+
+SECTIONS {
+    . = 0x100000;
+
+    . += SIZEOF_HEADERS;
+    . = ALIGN(4096);
+
+    .text : {
+        __text_start = .;
+        *(.text*)
+        . = ALIGN(4096);
+        __text_end = .;
+    }
+
+    .rodata : {
+        __rodata_start = .;
+        *(.rodata*)
+        . = ALIGN(4096);
+        __rodata_end = .;
+    }
+
+    .data : {
+        __data_start = .;
+        *(.data*)
+        . = ALIGN(4096);
+        __data_end = .;
+        __bss_start = .;
+        *(.bss*)
+        . = ALIGN(4096);
+        __bss_end = .;
+    }
+
+    .tdata : {
+        __tdata_start = .;
+        *(.tdata*)
+        . = ALIGN(4096);
+        __tdata_end = .;
+        __tbss_start = .;
+        *(.tbss*)
+        . += 8;
+        . = ALIGN(4096);
+        __tbss_end = .;
+    }
+
+    __end = .;
+
+    /DISCARD/ : {
+        *(.comment*)
+        *(.eh_frame*)
+        *(.gcc_except_table*)
+        *(.note*)
+        *(.rel.eh_frame*)
+    }
+}

rust-toolchain

+nightly-2021-06-15

src/lib.rs

+#![no_std]
+#![feature(lang_items)]
+#![feature(llvm_asm)]
+
+mod panic;
+
+#[no_mangle]
+pub unsafe extern "C" fn kstart() -> ! {
+    loop {}
+}

src/panic.rs

+//! Intrinsics for panic handling
+
+use core::alloc::Layout;
+use core::panic::PanicInfo;
+
+#[lang = "eh_personality"]
+#[no_mangle]
+pub extern "C" fn rust_eh_personality() {}
+
+/// Required to handle panics
+#[panic_handler]
+#[no_mangle]
+pub extern "C" fn rust_begin_unwind(info: &PanicInfo) -> ! {
+    //println!("BOOTLOADER PANIC: {}", info);
+    loop {
+        unsafe {
+            llvm_asm!("hlt" : : : : "intel", "volatile");
+        }
+    }
+}
+
+#[lang = "oom"]
+#[no_mangle]
+#[allow(improper_ctypes_definitions)] // Layout is not repr(C)
+pub extern fn rust_oom(_layout: Layout) -> ! {
+    panic!("kernel memory allocation failed");
+}
+
+#[allow(non_snake_case)]
+#[no_mangle]
+/// Required to handle panics
+pub extern "C" fn _Unwind_Resume() -> ! {
+    loop {
+        unsafe {
+            llvm_asm!("hlt" : : : : "intel", "volatile");
+        }
+    }
+}

targets/x86-unknown-none.json

+{
+    "llvm-target": "i686-unknown-none",
+    "target-endian": "little",
+    "target-pointer-width": "32",
+    "target-c-int-width": "32",
+    "data-layout": "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128",
+    "arch": "x86",
+    "os": "none",
+    "env": "",
+    "vendor": "unknown",
+    "linker-flavor": "gcc",
+    "target-family": "redox",
+    "pre-link-args": {
+        "gcc": ["-m32", "-nostdlib", "-static"]
+    },
+    "features": "-mmx,-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-3dnow,-3dnowa,-avx,-avx2,+soft-float",
+    "dynamic-linking": false,
+    "executables": false,
+    "relocation-model": "pic",
+    "code-model": "kernel",
+    "disable-redzone": true,
+    "eliminate-frame-pointer": false,
+    "exe-suffix": "",
+    "has-rpath": false,
+    "no-compiler-rt": true,
+    "no-default-libraries": true,
+    "position-independent-executables": false,
+    "has-elf-tls": true
+}

x86_64/disk.asm → x86/disk.asm

@@ -3,8 +3,8 @@ sectalign off
 %include "bootsector.asm"
 
 startup_start:
-%ifdef ARCH_i386
-    %include "startup-i386.asm"
+%ifdef ARCH_x86
+    %include "startup-x86.asm"
 %endif
 
 %ifdef ARCH_x86_64