Pass kernel command line option to logger

ostd/src/logger.rs

@@ -2,23 +2,20 @@
 
 //! Logging support.
 
-use log::{Level, Metadata, Record};
+use log::{LevelFilter, Metadata, Record};
 
-use crate::early_println;
+use crate::{
+    boot::{kcmdline::ModuleArg, kernel_cmdline},
+    early_println,
+};
 
 const LOGGER: Logger = Logger {};
 
-/// The log level.
-///
-/// FIXME: The logs should be able to be read from files in the userspace,
-/// and the log level should be configurable.
-pub const INIT_LOG_LEVEL: Level = Level::Error;
-
 struct Logger {}
 
 impl log::Log for Logger {
     fn enabled(&self, metadata: &Metadata) -> bool {
-        metadata.level() <= INIT_LOG_LEVEL
+        metadata.level() <= log::max_level()
     }
 
     fn log(&self, record: &Record) {
@@ -30,8 +27,33 @@ impl log::Log for Logger {
     fn flush(&self) {}
 }
 
+/// Initialize the logger. Users should avoid using the log macros before this function is called.
 pub(crate) fn init() {
-    log::set_logger(&LOGGER)
-        .map(|()| log::set_max_level(INIT_LOG_LEVEL.to_level_filter()))
-        .unwrap();
+    let level = get_log_level().unwrap_or(LevelFilter::Off);
+
+    log::set_max_level(level);
+    log::set_logger(&LOGGER).unwrap();
+}
+
+fn get_log_level() -> Option<LevelFilter> {
+    let module_args = kernel_cmdline().get_module_args("ostd")?;
+
+    let arg = module_args.iter().find(|arg| match arg {
+        ModuleArg::Arg(_) => false,
+        ModuleArg::KeyVal(name, _) => name.as_bytes() == "log_level".as_bytes(),
+    })?;
+
+    let ModuleArg::KeyVal(_, value) = arg else {
+        unreachable!()
+    };
+    let value = value.as_c_str().to_str().unwrap_or("off");
+    Some(match value {
+        "error" => LevelFilter::Error,
+        "warn" => LevelFilter::Warn,
+        "info" => LevelFilter::Info,
+        "debug" => LevelFilter::Debug,
+        "trace" => LevelFilter::Trace,
+        // Otherwise, OFF
+        _ => LevelFilter::Off,
+    })
 }