Merge #53

53: Updates for new build system r=phil-opp a=phil-opp

Update the documentation for the new build system and add an `example-kernel` that provides an easy way to try the `bootloader`.

Builds upon #51.

Co-authored-by: Philipp Oppermann <dev@phil-opp.com>

Changelog.md

@@ -1,3 +1,9 @@
+## Breaking
+
+- Change the build system: Use a build script that expects a `KERNEL` environment variable instead of using a separate `builder` executable as before. See [#51](https://github.com/rust-osdev/bootloader/pull/51) and [#53](https://github.com/rust-osdev/bootloader/pull/53) for more information.
+  - This makes the bootloader incompatible with versions `0.6.*` and earlier of the `bootimage` tool.
+  - The bootloader also requires the `llvm-tools-preview` rustup component now.
+
 # 0.4.0
 
 ## Breaking

README.md

@@ -10,28 +10,50 @@ Written for the [second edition](https://github.com/phil-opp/blog_os/issues/360)
 
 TODO
 
-## Build and Run
-You need a nightly [Rust](https://www.rust-lang.org) compiler and [cargo xbuild](https://github.com/rust-osdev/cargo-xbuild).
+## Requirements
 
-Then you can run the `builder` executable with your kernel as argument:
+You need a nightly [Rust](https://www.rust-lang.org) compiler and [cargo xbuild](https://github.com/rust-osdev/cargo-xbuild). You also need the `llvm-tools-preview` component, which can be installed through `rustup component add llvm-tools-preview`.
+
+## Build
+
+The simplest way to use the bootloader is in combination with the [bootimage](https://github.com/rust-osdev/bootimage) tool. With the tool installed, you can add a normal cargo dependency on the `bootloader` crate to your kernel and then run `bootimage build` to create a bootable disk image. You can also execute `bootimage run` to run your kernel in [QEMU](https://www.qemu.org/) (needs to be installed).
+
+To compile the bootloader manually, you need to invoke `cargo xbuild` with a `KERNEL` environment variable that points to your kernel executable (in the ELF format):
 
 ```
-cd builder
-cargo run -- --kernel path/to/your/kernel/elf/file
+KERNEL=/path/to/your/kernel/target/debug/your_kernel cargo xbuild
 ```
 
-This will output a file named `bootimage.bin` in the `../target/x86_64-bootloader/release` folder.
+As an example, you can build the bootloader with example kernel from the `example-kernel` directory with the following commands:
 
-You can run this file using [QEMU](https://www.qemu.org/):
+```
+cd example-kernel
+cargo xbuild
+cd ..
+KERNEL=example-kernel/target/x86_64-example-kernel/debug/example-kernel cargo xbuild --release
+```
+
+This results in a bootloader executable at `target/x86_64-bootloader.json/release/bootloader`. This executable is still an ELF file, which can't be run directly.
+
+## Run
+
+To run the compiled bootloader executable, you need to convert it to a binary file. You can use the `llvm-objcopy` tools that ships with the `llvm-tools-preview` rustup component. The easiest way to use this tool is using [`cargo-binutils`](https://github.com/rust-embedded/cargo-binutils), which can be installed through `cargo install cargo-binutils`. Then you can perform the conversion with the following command:
 
 ```
-qemu-system-x86_64 -drive format=raw,file=target/x86_64-bootloader/release/bootimage.bin
+cargo objcopy -- -I elf64-x86-64 -O binary --binary-architecture=i386:x86-64 \
+  target/x86_64-bootloader/release/bootloader target/x86_64-bootloader/release/bootloader.bin
 ```
 
-Or burn it to an USB drive:
+You can run the `bootloader.bin` file using [QEMU](https://www.qemu.org/):
 
 ```
-dd if=target/x86_64-blog_os/debug/bootimage-blog_os.bin of=/dev/sdX && sync
+qemu-system-x86_64 -drive format=raw,file=target/x86_64-bootloader/release/bootloader.bin
+```
+
+Or burn it to an USB drive to boot it on real hardware:
+
+```
+dd if=target/x86_64-bootloader/release/bootloader.bin of=/dev/sdX && sync
 ```
 
 Where sdX is the device name of your USB stick. **Be careful** to choose the correct device name, because everything on that device is overwritten.
@@ -40,3 +62,17 @@ Where sdX is the device name of your USB stick. **Be careful** to choose the cor
 The bootloader crate can be configured through some cargo features:
 
 - `vga_320x200`: This feature switches the VGA hardware to mode 0x13, a graphics mode with resolution 320x200 and 256 colors per pixel. The framebuffer is linear and lives at address `0xa0000`.
+- `recursive_page_table`: Maps the level 4 page table recursively and adds the [`recursive_page_table_address`](https://docs.rs/bootloader/0.4.0/bootloader/bootinfo/struct.BootInfo.html#structfield.recursive_page_table_addr) field to the passed `BootInfo`.
+- `map_physical_memory`: Maps the complete physical memory in the virtual address space and passes a [`physical_memory_offset`](https://docs.rs/bootloader/0.4.0/bootloader/bootinfo/struct.BootInfo.html#structfield.physical_memory_offset) field in the `BootInfo`.
+
+## License
+
+Licensed under either of
+
+- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or
+  http://www.apache.org/licenses/LICENSE-2.0)
+- MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+
+at your option.
+
+Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

azure-pipelines.yml

@@ -90,13 +90,13 @@ steps:
   failOnStderr: true
   displayName: 'Install QEMU (Windows)'
 
-- script: cargo xbuild --target x86_64-example-kernel.json
-  workingDirectory: example-kernel
-  displayName: 'Build Example Kernel'
+- script: cargo xbuild
+  workingDirectory: test-kernel
+  displayName: 'Build Test Kernel'
 
 - script: cargo xbuild --release
   displayName: 'Build Bootloader'
-  env: { KERNEL: "example-kernel/target/x86_64-example-kernel/debug/example-kernel" }
+  env: { KERNEL: "test-kernel/target/x86_64-test-kernel/debug/test-kernel" }
 
 - script: cargo objcopy -- -I elf64-x86-64 -O binary --binary-architecture=i386:x86-64 target/x86_64-bootloader/release/bootloader target/x86_64-bootloader/release/bootloader.bin
   displayName: 'Convert Bootloader ELF to Binary'
@@ -106,3 +106,6 @@ steps:
     if [ $? -eq 123 ]; then (exit 0); else (exit 1); fi
   displayName: 'Test Bootloader'
 
+- script: cargo xbuild
+  workingDirectory: example-kernel
+  displayName: 'Build Example Kernel'

example-kernel/.cargo/config

@@ -0,0 +1,2 @@
+[build]
+target = "x86_64-example-kernel.json"

example-kernel/src/main.rs

@@ -3,26 +3,29 @@
 
 use core::panic::PanicInfo;
 
-/// This function is called on panic.
-#[panic_handler]
-fn panic(_info: &PanicInfo) -> ! {
-    loop {}
-}
+static HELLO: &[u8] = b"Hello World!";
 
 #[no_mangle] // don't mangle the name of this function
 pub extern "C" fn _start() -> ! {
     // this function is the entry point, since the linker looks for a function
     // named `_start` by default
 
-    // exit QEMU (see https://os.phil-opp.com/integration-tests/#shutting-down-qemu)
-    unsafe { exit_qemu(); }
+    let vga_buffer = 0xb8000 as *mut u8;
+
+    // print `HELLO` to the screen (see
+    // https://os.phil-opp.com/minimal-rust-kernel/#printing-to-screen)
+    for (i, &byte) in HELLO.iter().enumerate() {
+        unsafe {
+            *vga_buffer.offset(i as isize * 2) = byte;
+            *vga_buffer.offset(i as isize * 2 + 1) = 0xb;
+        }
+    }
 
     loop {}
 }
 
-pub unsafe fn exit_qemu() {
-    use x86_64::instructions::port::Port;
-
-    let mut port = Port::<u32>::new(0xf4);
-    port.write(61); // exit code is (61 << 1) | 1 = 123
+/// This function is called on panic.
+#[panic_handler]
+fn panic(_info: &PanicInfo) -> ! {
+    loop {}
 }

rust-toolchain

@@ -0,0 +1 @@
+nightly

test-kernel/.cargo/config

@@ -0,0 +1,2 @@
+[build]
+target = "x86_64-test-kernel.json"

test-kernel/.gitignore

@@ -0,0 +1,2 @@
+/target/
+**/*.rs.bk

test-kernel/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "test-kernel"
+version = "0.1.0"
+authors = ["Philipp Oppermann <dev@phil-opp.com>"]
+edition = "2018"
+
+[dependencies]
+x86_64 = "0.3.4"

test-kernel/src/main.rs

@@ -0,0 +1,28 @@
+#![no_std] // don't link the Rust standard library
+#![no_main] // disable all Rust-level entry points
+
+use core::panic::PanicInfo;
+
+/// This function is called on panic.
+#[panic_handler]
+fn panic(_info: &PanicInfo) -> ! {
+    loop {}
+}
+
+#[no_mangle] // don't mangle the name of this function
+pub extern "C" fn _start() -> ! {
+    // this function is the entry point, since the linker looks for a function
+    // named `_start` by default
+
+    // exit QEMU (see https://os.phil-opp.com/integration-tests/#shutting-down-qemu)
+    unsafe { exit_qemu(); }
+
+    loop {}
+}
+
+pub unsafe fn exit_qemu() {
+    use x86_64::instructions::port::Port;
+
+    let mut port = Port::<u32>::new(0xf4);
+    port.write(61); // exit code is (61 << 1) | 1 = 123
+}

test-kernel/x86_64-test-kernel.json

@@ -0,0 +1,15 @@
+{
+    "llvm-target": "x86_64-unknown-none",
+    "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
+    "arch": "x86_64",
+    "target-endian": "little",
+    "target-pointer-width": "64",
+    "target-c-int-width": "32",
+    "os": "none",
+    "executables": true,
+    "linker-flavor": "ld.lld",
+    "linker": "rust-lld",
+    "panic-strategy": "abort",
+    "disable-redzone": true,
+    "features": "-mmx,-sse,+soft-float"
+  }