Print panic message when basic_boot test panics

Author: phil-opp

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

@@ -13,6 +13,9 @@ fn kernel_main(_boot_info: &'static mut BootInfo) -> ! {
 
 /// This function is called on panic.
 #[panic_handler]
-fn panic(_info: &PanicInfo) -> ! {
+fn panic(info: &PanicInfo) -> ! {
+    use core::fmt::Write;
+
+    let _ = writeln!(test_kernel_default_settings::serial(), "PANIC: {}", info);
     exit_qemu(QemuExitCode::Failed);
 }