feat(logging): align log envvars with the log crate

Author: cagatay-y

README.md

@@ -38,13 +38,16 @@ If you want to build the kernel for riscv64, please use `riscv64`.
 ### Control the kernel messages verbosity
 
 This kernel uses the lightweight logging crate [log](https://github.com/rust-lang/log) to print kernel messages. The
-environment variable `HERMIT_LOG_LEVEL_FILTER` controls the verbosity and follows [the env_logger
-format](https://docs.rs/env_logger/latest/env_logger/) but without the regex support. You can change it per module by
-setting it at compile time to a string in the format `[target][=level][,...]`, where the level is a string matching the
-name of a [LevelFilter](https://docs.rs/log/0.4.8/log/enum.LevelFilter.html). If the target is omitted, the level is set
-as the global level. If the level is omitted, logs of all levels are printed for the target.
+compile time environment variable `HERMIT_LOG_DEFAULT` and the runtime environment variable `HERMIT_LOG` control the
+verbosity and follow [the env_logger format](https://docs.rs/env_logger/latest/env_logger/) but without the regex
+support.
 
-If the variable is not set, or it does not provide a global level, then `LevelFilter::Info` is used as the global level
+The logging level can be changed per module by setting it to a string in the format `[target][=level][,...]`, where the
+level is a string matching the name of a [LevelFilter](https://docs.rs/log/0.4.8/log/enum.LevelFilter.html). If the
+target is omitted, the level is set as the global level. If the level is omitted, logs of all levels are printed for the
+target.
+
+If the variables are not set, or they do not provide a global level, then `LevelFilter::Info` is used as the global level
 by default.
 
 ```sh

src/arch/aarch64/kernel/mod.rs

@@ -90,7 +90,6 @@ pub fn boot_processor_init() {
 	crate::mm::init();
 	crate::mm::print_information();
 	CoreLocal::get().add_irq_counter();
-	env::init();
 	interrupts::init();
 	processor::detect_frequency();
 	crate::logging::KERNEL_LOGGER.set_time(true);

src/arch/riscv64/kernel/mod.rs

@@ -108,7 +108,6 @@ pub fn boot_processor_init() {
 	devicetree::init();
 	crate::mm::init();
 	crate::mm::print_information();
-	env::init();
 	interrupts::install();
 
 	finish_processor_init();

src/arch/x86_64/kernel/mod.rs

@@ -104,7 +104,6 @@ pub fn boot_processor_init() {
 	crate::mm::init();
 	crate::mm::print_information();
 	CoreLocal::get().add_irq_counter();
-	env::init();
 	gdt::add_current_core();
 	interrupts::load_idt();
 	pic::init();

src/logging.rs

@@ -6,6 +6,8 @@ use anstyle::AnsiColor;
 use hermit_sync::OnceCell;
 use log::{Level, LevelFilter, Metadata, Record};
 
+use crate::env;
+
 pub static KERNEL_LOGGER: KernelLogger = KernelLogger::new();
 const ARENA_SIZE: usize = 4096;
 static mut ARENA: [u8; ARENA_SIZE] = [0; _];
@@ -115,31 +117,38 @@ fn no_color() -> bool {
 }
 
 pub unsafe fn init() {
+	log::set_logger(&KERNEL_LOGGER).expect("Can't initialize logger");
+	// To get logs until we determine the actual log level
+	log::set_max_level(LevelFilter::Info);
+
 	#[cfg(target_os = "none")]
 	unsafe {
 		crate::mm::ALLOCATOR
 			.lock()
 			.claim((&raw mut ARENA).cast(), ARENA_SIZE)
 			.unwrap()
 	};
+	env::init();
+
+	let mut filter_builder = env_filter::Builder::new();
+	// The default. It may get overwritten by the parsed filter if it has a global level.
+	filter_builder.filter_level(LevelFilter::Info);
+
+	if let Some(compile_time_filter) = option_env!("HERMIT_LOG_DEFAULT").or_else(|| {
+		option_env!("HERMIT_LOG_LEVEL_FILTER").inspect(|_| {
+			warn!("HERMIT_LOG_LEVEL_FILTER is deprecated in favor of HERMIT_LOG_DEFAULT");
+		})
+	}) {
+		filter_builder.parse(compile_time_filter);
+	}
 
-	log::set_logger(&KERNEL_LOGGER).expect("Can't initialize logger");
-	// Determines LevelFilter at compile time
-	let log_level: Option<&'static str> = option_env!("HERMIT_LOG_LEVEL_FILTER");
-	let max_level = if let Some(log_level) = log_level {
-		let filter = env_filter::Builder::new()
-			// The default. It may get overwritten by the parsed filter if it has a global level.
-			.filter_level(LevelFilter::Info)
-			.parse(log_level)
-			.build();
-		let max_level = filter.filter();
-		KERNEL_LOGGER.filter.set(filter).unwrap();
-		max_level
-	} else {
-		LevelFilter::Info
-	};
+	if let Some(runtime_filter) = env::var("HERMIT_LOG") {
+		filter_builder.parse(runtime_filter);
+	}
 
-	log::set_max_level(max_level);
+	let filter = filter_builder.build();
+	log::set_max_level(filter.filter());
+	KERNEL_LOGGER.filter.set(filter).unwrap();
 }
 
 #[cfg_attr(target_arch = "riscv64", allow(unused))]