Test booting with a minimal kernel stack size

Author: phil-opp

Cargo.lock

@@ -24,6 +24,7 @@ members = [
     "tests/test_kernels/pie",
     "tests/test_kernels/lto",
     "tests/test_kernels/ramdisk",
+    "tests/test_kernels/min_stack",
 ]
 exclude = ["examples/basic", "examples/test_framework"]
 
@@ -60,6 +61,7 @@ test_kernel_higher_half = { path = "tests/test_kernels/higher_half", artifact =
 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" }
 test_kernel_ramdisk = { path = "tests/test_kernels/ramdisk", artifact = "bin", target = "x86_64-unknown-none" }
+test_kernel_min_stack = { path = "tests/test_kernels/min_stack", artifact = "bin", target = "x86_64-unknown-none" }
 
 [profile.dev]
 panic = "abort"
@@ -113,6 +115,9 @@ rustflags = [
     "code-model=large",
 ]
 
+[profile.test.package.test_kernel_min_stack]
+opt-level = 2
+
 [build-dependencies]
 llvm-tools = "0.1.1"
 async-process = "1.6.0"

Cargo.toml

@@ -0,0 +1,6 @@
+use bootloader_test_runner::run_test_kernel;
+
+#[test]
+fn basic_boot() {
+    run_test_kernel(env!("CARGO_BIN_FILE_TEST_KERNEL_MIN_STACK_basic_boot"));
+}

tests/min_stack.rs

@@ -0,0 +1,13 @@
+[package]
+name = "test_kernel_min_stack"
+version = "0.1.0"
+authors = ["Philipp Oppermann <dev@phil-opp.com>"]
+edition = "2021"
+
+[dependencies]
+bootloader_api = { path = "../../../api" }
+x86_64 = { version = "0.14.7", default-features = false, features = [
+    "instructions",
+    "inline_asm",
+] }
+uart_16550 = "0.2.10"

tests/test_kernels/min_stack/Cargo.toml

@@ -0,0 +1,26 @@
+#![no_std] // don't link the Rust standard library
+#![no_main] // disable all Rust-level entry points
+
+use bootloader_api::{entry_point, BootInfo, BootloaderConfig};
+use core::fmt::Write;
+use test_kernel_min_stack::{exit_qemu, serial, QemuExitCode};
+
+const BOOTLOADER_CONFIG: BootloaderConfig = {
+    let mut config = BootloaderConfig::new_default();
+    config.kernel_stack_size = 3000;
+    config
+};
+entry_point!(kernel_main, config = &BOOTLOADER_CONFIG);
+
+fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
+    writeln!(serial(), "Entered kernel with boot info: {boot_info:?}").unwrap();
+    exit_qemu(QemuExitCode::Success);
+}
+
+/// This function is called on panic.
+#[panic_handler]
+#[cfg(not(test))]
+fn panic(info: &core::panic::PanicInfo) -> ! {
+    let _ = writeln!(serial(), "PANIC: {info}");
+    exit_qemu(QemuExitCode::Failed);
+}

tests/test_kernels/min_stack/src/bin/basic_boot.rs

@@ -0,0 +1,27 @@
+#![no_std]
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(u32)]
+pub enum QemuExitCode {
+    Success = 0x10,
+    Failed = 0x11,
+}
+
+pub fn exit_qemu(exit_code: QemuExitCode) -> ! {
+    use x86_64::instructions::{nop, port::Port};
+
+    unsafe {
+        let mut port = Port::new(0xf4);
+        port.write(exit_code as u32);
+    }
+
+    loop {
+        nop();
+    }
+}
+
+pub fn serial() -> uart_16550::SerialPort {
+    let mut port = unsafe { uart_16550::SerialPort::new(0x3F8) };
+    port.init();
+    port
+}