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README.ES.md -> 03_hacky_hello_world

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# Tutorial 03 - Hacky Hello World
## tl;dr
* Introduciendo la macro global `print!()` para habilitar "printf debugging" lo más pronto posible.
* Para mantener una duración razonable en este tutorial, imprimir funciones por el momento "abusa" una propiedad de QEMU que nos permite hacer uso del `UART` de la Raspberry sin haberla configurado apropiadamente.
* Usar el hardware real de `UART` se habilitará paso por paso en los siguientes tutoriales.
## Adiciones notables
* `src/console.rs` introduce la interfaz `Traits` para comandos de consola.
* `src/bsp/raspberrypi/console.rs` implementa la interfaz para que QEMU pueda crear una emulación de UART.
* El *panic handler* (manipulador de pánico) hace uso de la nueva macro `print!()` para mostrar mensajes de error del usuario.
* Hay un nuevo objetivo Makefile, `make test`, destinado a la automatización de pruebas. Este comando inicia el kernel (núcleo) compilado en `QEMU`, y busca una cadena específica que ha sido producida por el kernel (núcleo).
* En este tutorial, se buscará la cadena `Stopping here`, que es creada por la macro `panic!()` al final del archivo `main.rs`.
## Pruébalo
QEMU ya no está siendo ejecutado en modo ensamblador. Desde ahora en adelante mostrará la salida de la `consola`.
```console
$ make qemu
[...]
Hello from Rust!
Kernel panic: Stopping here.
```
### Diccionario
* *Hacky:* Solución torpe o poco elegante para un problema.
* *Debugging:* Proceso para identificar y corregir errores de programación.
* *printf debugging:* Usado para describir el trabajo de *debugging* poniendo comandos que dan una salida en consola, como el de "printf", en diferentes lugares del programa; observando la información y tratando de deducir qué está mal en el programa basandose en la información que nos da nuestros comandos.
* *Traits:* Un *trait* le hace saber al compilador de Rust acerca de una funcionalidad que tiene un tipo de dato particular y que puede compartir con otros tipos de datos.
> NOTA: Los *traits* son similares a una característica que se le conoce comúnmente como *interfaces* en otros lenguajes, aunque con algunas diferencias.
Si deseas aprender más acerca de esto, por favor lee este capítulo del libro de Rust: [Traits: Defining Shared Behavior - The Rust Programming Language](https://doc.rust-lang.org/book/ch10-02-traits.html)
## Diferencias con el archivo anterior
```diff
diff -uNr 02_runtime_init/Cargo.toml 03_hacky_hello_world/Cargo.toml
--- 02_runtime_init/Cargo.toml
+++ 03_hacky_hello_world/Cargo.toml
@@ -1,6 +1,6 @@
[package]
name = "mingo"
-version = "0.2.0"
+version = "0.3.0"
authors = ["Andre Richter <andre.o.richter@gmail.com>"]
edition = "2021"
diff -uNr 02_runtime_init/Makefile 03_hacky_hello_world/Makefile
--- 02_runtime_init/Makefile
+++ 03_hacky_hello_world/Makefile
@@ -24,7 +24,7 @@
KERNEL_BIN = kernel8.img
QEMU_BINARY = qemu-system-aarch64
QEMU_MACHINE_TYPE = raspi3
- QEMU_RELEASE_ARGS = -d in_asm -display none
+ QEMU_RELEASE_ARGS = -serial stdio -display none
OBJDUMP_BINARY = aarch64-none-elf-objdump
NM_BINARY = aarch64-none-elf-nm
READELF_BINARY = aarch64-none-elf-readelf
@@ -35,7 +35,7 @@
KERNEL_BIN = kernel8.img
QEMU_BINARY = qemu-system-aarch64
QEMU_MACHINE_TYPE =
- QEMU_RELEASE_ARGS = -d in_asm -display none
+ QEMU_RELEASE_ARGS = -serial stdio -display none
OBJDUMP_BINARY = aarch64-none-elf-objdump
NM_BINARY = aarch64-none-elf-nm
READELF_BINARY = aarch64-none-elf-readelf
@@ -71,17 +71,20 @@
--strip-all \
-O binary
-EXEC_QEMU = $(QEMU_BINARY) -M $(QEMU_MACHINE_TYPE)
+EXEC_QEMU = $(QEMU_BINARY) -M $(QEMU_MACHINE_TYPE)
+EXEC_TEST_DISPATCH = ruby ../common/tests/dispatch.rb
##------------------------------------------------------------------------------
## Dockerization
##------------------------------------------------------------------------------
-DOCKER_CMD = docker run -t --rm -v $(shell pwd):/work/tutorial -w /work/tutorial
-DOCKER_CMD_INTERACT = $(DOCKER_CMD) -i
+DOCKER_CMD = docker run -t --rm -v $(shell pwd):/work/tutorial -w /work/tutorial
+DOCKER_CMD_INTERACT = $(DOCKER_CMD) -i
+DOCKER_ARG_DIR_COMMON = -v $(shell pwd)/../common:/work/common
# DOCKER_IMAGE defined in include file (see top of this file).
DOCKER_QEMU = $(DOCKER_CMD_INTERACT) $(DOCKER_IMAGE)
DOCKER_TOOLS = $(DOCKER_CMD) $(DOCKER_IMAGE)
+DOCKER_TEST = $(DOCKER_CMD) $(DOCKER_ARG_DIR_COMMON) $(DOCKER_IMAGE)
@@ -169,3 +172,28 @@
##------------------------------------------------------------------------------
check:
@RUSTFLAGS="$(RUSTFLAGS)" $(CHECK_CMD) --message-format=json
+
+
+
+##--------------------------------------------------------------------------------------------------
+## Testing targets
+##--------------------------------------------------------------------------------------------------
+.PHONY: test test_boot
+
+ifeq ($(QEMU_MACHINE_TYPE),) # QEMU is not supported for the board.
+
+test_boot test :
+ $(call colorecho, "\n$(QEMU_MISSING_STRING)")
+
+else # QEMU is supported.
+
+##------------------------------------------------------------------------------
+## Run boot test
+##------------------------------------------------------------------------------
+test_boot: $(KERNEL_BIN)
+ $(call colorecho, "\nBoot test - $(BSP)")
+ @$(DOCKER_TEST) $(EXEC_TEST_DISPATCH) $(EXEC_QEMU) $(QEMU_RELEASE_ARGS) -kernel $(KERNEL_BIN)
+
+test: test_boot
+
+endif
diff -uNr 02_runtime_init/src/bsp/raspberrypi/console.rs 03_hacky_hello_world/src/bsp/raspberrypi/console.rs
--- 02_runtime_init/src/bsp/raspberrypi/console.rs
+++ 03_hacky_hello_world/src/bsp/raspberrypi/console.rs
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+//
+// Copyright (c) 2018-2022 Andre Richter <andre.o.richter@gmail.com>
+
+//! BSP console facilities.
+
+use crate::console;
+use core::fmt;
+
+//--------------------------------------------------------------------------------------------------
+// Private Definitions
+//--------------------------------------------------------------------------------------------------
+
+/// A mystical, magical device for generating QEMU output out of the void.
+struct QEMUOutput;
+
+//--------------------------------------------------------------------------------------------------
+// Private Code
+//--------------------------------------------------------------------------------------------------
+
+/// Implementing `core::fmt::Write` enables usage of the `format_args!` macros, which in turn are
+/// used to implement the `kernel`'s `print!` and `println!` macros. By implementing `write_str()`,
+/// we get `write_fmt()` automatically.
+///
+/// See [`src/print.rs`].
+///
+/// [`src/print.rs`]: ../../print/index.html
+impl fmt::Write for QEMUOutput {
+ fn write_str(&mut self, s: &str) -> fmt::Result {
+ for c in s.chars() {
+ unsafe {
+ core::ptr::write_volatile(0x3F20_1000 as *mut u8, c as u8);
+ }
+ }
+
+ Ok(())
+ }
+}
+
+//--------------------------------------------------------------------------------------------------
+// Public Code
+//--------------------------------------------------------------------------------------------------
+
+/// Return a reference to the console.
+pub fn console() -> impl console::interface::Write {
+ QEMUOutput {}
+}
diff -uNr 02_runtime_init/src/bsp/raspberrypi.rs 03_hacky_hello_world/src/bsp/raspberrypi.rs
--- 02_runtime_init/src/bsp/raspberrypi.rs
+++ 03_hacky_hello_world/src/bsp/raspberrypi.rs
@@ -4,4 +4,5 @@
//! Top-level BSP file for the Raspberry Pi 3 and 4.
+pub mod console;
pub mod cpu;
diff -uNr 02_runtime_init/src/console.rs 03_hacky_hello_world/src/console.rs
--- 02_runtime_init/src/console.rs
+++ 03_hacky_hello_world/src/console.rs
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+//
+// Copyright (c) 2018-2022 Andre Richter <andre.o.richter@gmail.com>
+
+//! System console.
+
+//--------------------------------------------------------------------------------------------------
+// Public Definitions
+//--------------------------------------------------------------------------------------------------
+
+/// Console interfaces.
+pub mod interface {
+ /// Console write functions.
+ ///
+ /// `core::fmt::Write` is exactly what we need for now. Re-export it here because
+ /// implementing `console::Write` gives a better hint to the reader about the
+ /// intention.
+ pub use core::fmt::Write;
+}
diff -uNr 02_runtime_init/src/main.rs 03_hacky_hello_world/src/main.rs
--- 02_runtime_init/src/main.rs
+++ 03_hacky_hello_world/src/main.rs
@@ -104,12 +104,16 @@
//! - It is implemented in `src/_arch/__arch_name__/cpu/boot.s`.
//! 2. Once finished with architectural setup, the arch code calls `kernel_init()`.
+#![feature(format_args_nl)]
+#![feature(panic_info_message)]
#![no_main]
#![no_std]
mod bsp;
+mod console;
mod cpu;
mod panic_wait;
+mod print;
/// Early init code.
///
@@ -117,5 +121,7 @@
///
/// - Only a single core must be active and running this function.
unsafe fn kernel_init() -> ! {
- panic!()
+ println!("[0] Hello from Rust!");
+
+ panic!("Stopping here.")
}
diff -uNr 02_runtime_init/src/panic_wait.rs 03_hacky_hello_world/src/panic_wait.rs
--- 02_runtime_init/src/panic_wait.rs
+++ 03_hacky_hello_world/src/panic_wait.rs
@@ -4,10 +4,16 @@
//! A panic handler that infinitely waits.
-use crate::cpu;
+use crate::{cpu, println};
use core::panic::PanicInfo;
#[panic_handler]
-fn panic(_info: &PanicInfo) -> ! {
+fn panic(info: &PanicInfo) -> ! {
+ if let Some(args) = info.message() {
+ println!("\nKernel panic: {}", args);
+ } else {
+ println!("\nKernel panic!");
+ }
+
cpu::wait_forever()
}
diff -uNr 02_runtime_init/src/print.rs 03_hacky_hello_world/src/print.rs
--- 02_runtime_init/src/print.rs
+++ 03_hacky_hello_world/src/print.rs
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+//
+// Copyright (c) 2018-2022 Andre Richter <andre.o.richter@gmail.com>
+
+//! Printing.
+
+use crate::{bsp, console};
+use core::fmt;
+
+//--------------------------------------------------------------------------------------------------
+// Public Code
+//--------------------------------------------------------------------------------------------------
+
+#[doc(hidden)]
+pub fn _print(args: fmt::Arguments) {
+ use console::interface::Write;
+
+ bsp::console::console().write_fmt(args).unwrap();
+}
+
+/// Prints without a newline.
+///
+/// Carbon copy from <https://doc.rust-lang.org/src/std/macros.rs.html>
+#[macro_export]
+macro_rules! print {
+ ($($arg:tt)*) => ($crate::print::_print(format_args!($($arg)*)));
+}
+
+/// Prints with a newline.
+///
+/// Carbon copy from <https://doc.rust-lang.org/src/std/macros.rs.html>
+#[macro_export]
+macro_rules! println {
+ () => ($crate::print!("\n"));
+ ($($arg:tt)*) => ({
+ $crate::print::_print(format_args_nl!($($arg)*));
+ })
+}
diff -uNr 02_runtime_init/tests/boot_test_string.rb 03_hacky_hello_world/tests/boot_test_string.rb
--- 02_runtime_init/tests/boot_test_string.rb
+++ 03_hacky_hello_world/tests/boot_test_string.rb
@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+EXPECTED_PRINT = 'Stopping here'
```
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