Start integrating BIOS bootloader into build system

We can use an artifact dependency on the outer level since the x86_64-unknown-none target is Tier 2 and thus requires no -Zbuild-std. For the boot_sector, we need to compile with a specific linker script and profile. We might need to duplicate the profile settings in the boot_sector Cargo.toml when publishing.
rust-osdev · phil-opp · Nov 13, 2022 · Dec 13, 2019 · Dec 14, 2019 · Dec 20, 2019
commit eb6d71f244c54031bddbf87042d710bcdd1aa0bb
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/Cargo.toml b/Cargo.toml
@@ -15,7 +15,7 @@ members = [
     "common",
     "uefi",
     "bios",
-    "bios/first_stage",
+    "bios/boot_sector",
     "tests/runner",
     "tests/test_kernels/default_settings",
     "tests/test_kernels/map_phys_mem",
@@ -30,20 +30,19 @@ anyhow = "1.0.32"
 fatfs = "0.3.4"
 gpt = "3.0.0"
 
+[dependencies.bootloader-x86_64-bios]
+version = "0.1.0-alpha.0"
+path = "bios"
+artifact = ["bin"]
+target = "x86_64-unknown-none"
+
 [dev-dependencies]
 bootloader_test_runner = { path = "tests/runner" }
 test_kernel_default_settings = { path = "tests/test_kernels/default_settings", artifact = "bin", target = "x86_64-unknown-none" }
 test_kernel_higher_half = { path = "tests/test_kernels/higher_half", artifact = "bin", target = "x86_64-unknown-none" }
 test_kernel_map_phys_mem = { path = "tests/test_kernels/map_phys_mem", artifact = "bin", target = "x86_64-unknown-none" }
 test_kernel_pie = { path = "tests/test_kernels/pie", artifact = "bin", target = "x86_64-unknown-none" }
 
-# [dependencies.bootloader-x86_64-uefi]
-# version = "0.1.0"
-# path = "uefi"
-# artifact = ["bin"]
-# target = "x86_64-unknown-uefi"
-
-
 [profile.dev]
 panic = "abort"
 

diff --git a/bios/Cargo.toml b/bios/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "bootloader-x86_64-bios"
-version = "0.1.0"
+version = "0.1.0-alpha.0"
 edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

diff --git a/bios/first_stage/.gitignore → bios/boot_sector/.gitignore b/bios/first_stage/.gitignore → bios/boot_sector/.gitignore
diff --git a/bios/first_stage/16-bit-linker.ld → bios/boot_sector/16-bit-linker.ld b/bios/first_stage/16-bit-linker.ld → bios/boot_sector/16-bit-linker.ld
diff --git a/bios/first_stage/Cargo.toml → bios/boot_sector/Cargo.toml b/bios/first_stage/Cargo.toml → bios/boot_sector/Cargo.toml
@@ -1,5 +1,5 @@
 [package]
-name = "bootloader_first_stage"
+name = "bootloader-x86_64-bios-boot-sector"
 version = "0.1.0"
 authors = ["Philipp Oppermann <[email protected]>"]
 edition = "2021"

diff --git a/bios/first_stage/README.md → bios/boot_sector/README.md b/bios/first_stage/README.md → bios/boot_sector/README.md
diff --git a/bios/boot_sector/build.rs b/bios/boot_sector/build.rs
@@ -0,0 +1,9 @@
+use std::path::Path;
+
+fn main() {
+    let local_path = Path::new(env!("CARGO_MANIFEST_DIR"));
+    println!(
+        "cargo:rustc-link-arg-bins=--script={}",
+        local_path.join("16-bit-linker.ld").display()
+    )
+}
diff --git a/bios/first_stage/src/boot unreal.s → bios/boot_sector/src/boot unreal.s b/bios/first_stage/src/boot unreal.s → bios/boot_sector/src/boot unreal.s
diff --git a/bios/first_stage/src/boot.s → bios/boot_sector/src/boot.s b/bios/first_stage/src/boot.s → bios/boot_sector/src/boot.s
diff --git a/bios/first_stage/src/dap.rs → bios/boot_sector/src/dap.rs b/bios/first_stage/src/dap.rs → bios/boot_sector/src/dap.rs
diff --git a/bios/first_stage/src/fail.rs → bios/boot_sector/src/fail.rs b/bios/first_stage/src/fail.rs → bios/boot_sector/src/fail.rs
diff --git a/bios/first_stage/src/fat.rs → bios/boot_sector/src/fat.rs b/bios/first_stage/src/fat.rs → bios/boot_sector/src/fat.rs
diff --git a/bios/first_stage/src/main.rs → bios/boot_sector/src/main.rs b/bios/first_stage/src/main.rs → bios/boot_sector/src/main.rs
diff --git a/bios/first_stage/src/mbr.rs → bios/boot_sector/src/mbr.rs b/bios/first_stage/src/mbr.rs → bios/boot_sector/src/mbr.rs
diff --git a/bios/build.rs b/bios/build.rs
@@ -0,0 +1,52 @@
+use std::{
+    path::{Path, PathBuf},
+    process::Command,
+};
+
+const BOOTLOADER_X86_64_BIOS_BOOT_SECTOR_VERSION: &str = "0.1.0-alpha.0";
+
+fn main() {
+    let out_dir = PathBuf::from(std::env::var("OUT_DIR").unwrap());
+
+    let bios_boot_sector_path = build_bios_boot_sector(&out_dir);
+
+    println!(
+        "cargo:rustc-env=BIOS_BOOT_SECTOR_PATH={}",
+        bios_boot_sector_path.display()
+    );
+}
+
+fn build_bios_boot_sector(out_dir: &Path) -> PathBuf {
+    let cargo = std::env::var("CARGO").unwrap_or_else(|_| "cargo".into());
+    let mut cmd = Command::new(cargo);
+    cmd.arg("install").arg("bootloader-x86_64-bios-boot-sector");
+    let local_path = Path::new(env!("CARGO_MANIFEST_DIR")).join("boot_sector");
+    if local_path.exists() {
+        // local build
+        cmd.arg("--path").arg(&local_path);
+    } else {
+        cmd.arg("--version")
+            .arg(BOOTLOADER_X86_64_BIOS_BOOT_SECTOR_VERSION);
+    }
+    cmd.arg("--locked");
+    cmd.arg("--target").arg("x86-16bit.json");
+    cmd.arg("--profile").arg("first-stage");
+    cmd.arg("-Zbuild-std=core")
+        .arg("-Zbuild-std-features=compiler-builtins-mem");
+    cmd.arg("--root").arg(out_dir);
+    let status = cmd
+        .status()
+        .expect("failed to run cargo install for bios boot sector");
+    if status.success() {
+        let path = out_dir
+            .join("bin")
+            .join("bootloader-x86_64-bios-boot-sector");
+        assert!(
+            path.exists(),
+            "bios boot sector executable does not exist after building"
+        );
+        path
+    } else {
+        panic!("failed to build bios boot sector");
+    }
+}
diff --git a/bios/src/main.rs b/bios/src/main.rs
@@ -20,54 +20,6 @@ use x86_64::{PhysAddr, VirtAddr};
 
 mod memory_descriptor;
 
-global_asm!(include_str!("asm/stage_1.s"));
-global_asm!(include_str!("asm/stage_2.s"));
-global_asm!(include_str!("asm/vesa.s"));
-global_asm!(include_str!("asm/e820.s"));
-global_asm!(include_str!("asm/stage_3.s"));
-
-// values defined in `vesa.s`
-extern "C" {
-    static VBEModeInfo_physbaseptr: u32;
-    static VBEModeInfo_bytesperscanline: u16;
-    static VBEModeInfo_xresolution: u16;
-    static VBEModeInfo_yresolution: u16;
-    static VBEModeInfo_bitsperpixel: u8;
-    static VBEModeInfo_redfieldposition: u8;
-    static VBEModeInfo_greenfieldposition: u8;
-    static VBEModeInfo_bluefieldposition: u8;
-}
-
-// Symbols defined in `linker.ld`
-extern "C" {
-    static mmap_ent: usize;
-    static _memory_map: usize;
-    static _kernel_start_addr: usize;
-    static _kernel_end_addr: usize;
-    static _kernel_size: usize;
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn stage_4() -> ! {
-    // Set stack segment
-    asm!(
-        "mov ax, 0x0; mov ss, ax",
-        out("ax") _,
-    );
-
-    let kernel_start = 0x400000;
-    let kernel_size = &_kernel_size as *const _ as u64;
-    let memory_map_addr = &_memory_map as *const _ as u64;
-    let memory_map_entry_count = (mmap_ent & 0xff) as u64; // Extract lower 8 bits
-
-    bootloader_main(
-        PhysAddr::new(kernel_start),
-        kernel_size,
-        VirtAddr::new(memory_map_addr),
-        memory_map_entry_count,
-    )
-}
-
 fn bootloader_main(
     kernel_start: PhysAddr,
     kernel_size: u64,
@@ -119,40 +71,11 @@ fn bootloader_main(
         }
     }
 
-    let framebuffer_addr = PhysAddr::new(unsafe { VBEModeInfo_physbaseptr }.into());
-    let mut error = None;
-    let framebuffer_info = unsafe {
-        let framebuffer_size =
-            usize::from(VBEModeInfo_yresolution) * usize::from(VBEModeInfo_bytesperscanline);
-        let bytes_per_pixel = VBEModeInfo_bitsperpixel / 8;
-        init_logger(
-            framebuffer_addr,
-            framebuffer_size.into(),
-            VBEModeInfo_xresolution.into(),
-            VBEModeInfo_yresolution.into(),
-            bytes_per_pixel.into(),
-            (VBEModeInfo_bytesperscanline / u16::from(bytes_per_pixel)).into(),
-            match (
-                VBEModeInfo_redfieldposition,
-                VBEModeInfo_greenfieldposition,
-                VBEModeInfo_bluefieldposition,
-            ) {
-                (0, 8, 16) => PixelFormat::Rgb,
-                (16, 8, 0) => PixelFormat::Bgr,
-                (r, g, b) => {
-                    error = Some(("invalid rgb field positions", r, g, b));
-                    PixelFormat::Rgb // default to RBG so that we can print something
-                }
-            },
-        )
-    };
+    let framebuffer_addr = todo!();
+    let framebuffer_info = todo!();
 
     log::info!("BIOS boot");
 
-    if let Some((msg, r, g, b)) = error {
-        panic!("{}: r: {}, g: {}, b: {}", msg, r, g, b);
-    }
-
     let page_tables = create_page_tables(&mut frame_allocator);
 
     let kernel_slice = {