Log level feature (rust-osdev#303)

jasoncouture · Jan 3, 2023 · fffa7ce · fffa7ce
1 parent 66c1218
commit fffa7ce
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Showing 5 changed files with 84 additions and 16 deletions.
diff --git a/api/build.rs b/api/build.rs
@@ -22,6 +22,7 @@ fn main() {
         (88, 9),
         (97, 9),
         (106, 9),
+        (115, 1),
     ];
 
     let mut code = String::new();

diff --git a/api/src/config.rs b/api/src/config.rs
@@ -27,6 +27,10 @@ pub struct BootloaderConfig {
     /// Configuration for the frame buffer that can be used by the kernel to display pixels
     /// on the screen.
     pub frame_buffer: FrameBuffer,
+
+    /// Configuration for changing the level of the filter of the messages that are shown in the
+    /// screen when booting. The default is 'Trace'.
+    pub log_level: LevelFilter,
 }
 
 impl BootloaderConfig {
@@ -35,7 +39,7 @@ impl BootloaderConfig {
         0x3D,
     ];
     #[doc(hidden)]
-    pub const SERIALIZED_LEN: usize = 115;
+    pub const SERIALIZED_LEN: usize = 116;
 
     /// Creates a new default configuration with the following values:
     ///
@@ -48,6 +52,7 @@ impl BootloaderConfig {
             version: ApiVersion::new_default(),
             mappings: Mappings::new_default(),
             frame_buffer: FrameBuffer::new_default(),
+            log_level: LevelFilter::Trace,
         }
     }
 
@@ -61,6 +66,7 @@ impl BootloaderConfig {
             mappings,
             kernel_stack_size,
             frame_buffer,
+            log_level,
         } = self;
         let ApiVersion {
             version_major,
@@ -133,13 +139,15 @@ impl BootloaderConfig {
             },
         );
 
-        concat_106_9(
+        let buf = concat_106_9(
             buf,
             match minimum_framebuffer_width {
                 Option::None => [0; 9],
                 Option::Some(addr) => concat_1_8([1], addr.to_le_bytes()),
             },
-        )
+        );
+
+        concat_115_1(buf, (*log_level as u8).to_le_bytes())
     }
 
     /// Tries to deserialize a config byte array that was created using [`Self::serialize`].
@@ -252,6 +260,13 @@ impl BootloaderConfig {
             (frame_buffer, s)
         };
 
+        let (&log_level, s) = split_array_ref(s);
+        let log_level = LevelFilter::from_u8(u8::from_le_bytes(log_level));
+        let log_level = match log_level {
+            Option::Some(level) => level,
+            Option::None => return Err("log_level invalid"),
+        };
+
         if !s.is_empty() {
             return Err("unexpected rest");
         }
@@ -261,6 +276,7 @@ impl BootloaderConfig {
             kernel_stack_size: u64::from_le_bytes(kernel_stack_size),
             mappings,
             frame_buffer,
+            log_level,
         })
     }
 
@@ -271,6 +287,7 @@ impl BootloaderConfig {
             mappings: Mappings::random(),
             kernel_stack_size: rand::random(),
             frame_buffer: FrameBuffer::random(),
+            log_level: LevelFilter::Trace,
         }
     }
 }
@@ -534,6 +551,42 @@ impl Default for Mapping {
     }
 }
 
+/// An enum representing the available verbosity level filters of the logger.
+///
+/// Based on
+/// https://github.com/rust-lang/log/blob/dc32ab999f52805d5ce579b526bd9d9684c38d1a/src/lib.rs#L552-565
+#[repr(u8)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum LevelFilter {
+    /// A level lower than all log levels.
+    Off,
+    /// Corresponds to the `Error` log level.
+    Error,
+    /// Corresponds to the `Warn` log level.
+    Warn,
+    /// Corresponds to the `Info` log level.
+    Info,
+    /// Corresponds to the `Debug` log level.
+    Debug,
+    /// Corresponds to the `Trace` log level.
+    Trace,
+}
+
+impl LevelFilter {
+    /// Converts a u8 into a Option<LevelFilter>
+    pub fn from_u8(value: u8) -> Option<LevelFilter> {
+        match value {
+            0 => Some(Self::Off),
+            1 => Some(Self::Error),
+            2 => Some(Self::Warn),
+            3 => Some(Self::Info),
+            4 => Some(Self::Debug),
+            5 => Some(Self::Trace),
+            _ => None,
+        }
+    }
+}
+
 /// Taken from https://github.com/rust-lang/rust/blob/e100ec5bc7cd768ec17d75448b29c9ab4a39272b/library/core/src/slice/mod.rs#L1673-L1677
 ///
 /// TODO replace with `split_array` feature in stdlib as soon as it's stabilized,

diff --git a/bios/stage-4/src/main.rs b/bios/stage-4/src/main.rs
@@ -2,7 +2,10 @@
 #![no_main]
 
 use crate::memory_descriptor::MemoryRegion;
-use bootloader_api::info::{FrameBufferInfo, PixelFormat};
+use bootloader_api::{
+    config::LevelFilter,
+    info::{FrameBufferInfo, PixelFormat},
+};
 use bootloader_x86_64_bios_common::{BiosFramebufferInfo, BiosInfo, E820MemoryRegion};
 use bootloader_x86_64_common::RawFrameBufferInfo;
 use bootloader_x86_64_common::{
@@ -24,10 +27,6 @@ mod memory_descriptor;
 #[no_mangle]
 #[link_section = ".start"]
 pub extern "C" fn _start(info: &mut BiosInfo) -> ! {
-    let framebuffer_info = init_logger(info.framebuffer);
-    log::info!("4th Stage");
-    log::info!("{info:x?}");
-
     let memory_map: &mut [E820MemoryRegion] = unsafe {
         core::slice::from_raw_parts_mut(
             info.memory_map_addr as *mut _,
@@ -102,8 +101,6 @@ pub extern "C" fn _start(info: &mut BiosInfo) -> ! {
     // it's mapped using `invlpg`, for efficiency.
     x86_64::instructions::tlb::flush_all();
 
-    log::info!("BIOS boot");
-
     let page_tables = create_page_tables(&mut frame_allocator);
 
     let kernel_slice = {
@@ -112,6 +109,12 @@ pub extern "C" fn _start(info: &mut BiosInfo) -> ! {
     };
     let kernel = Kernel::parse(kernel_slice);
 
+    let framebuffer_info = init_logger(info.framebuffer, kernel.config.log_level);
+
+    log::info!("4th Stage");
+    log::info!("{info:x?}");
+    log::info!("BIOS boot");
+
     let system_info = SystemInfo {
         framebuffer: Some(RawFrameBufferInfo {
             addr: PhysAddr::new(info.framebuffer.region.start),
@@ -123,7 +126,7 @@ pub extern "C" fn _start(info: &mut BiosInfo) -> ! {
     load_and_switch_to_kernel(kernel, frame_allocator, page_tables, system_info);
 }
 
-fn init_logger(info: BiosFramebufferInfo) -> FrameBufferInfo {
+fn init_logger(info: BiosFramebufferInfo, log_level: LevelFilter) -> FrameBufferInfo {
     let framebuffer_info = FrameBufferInfo {
         byte_len: info.region.len.try_into().unwrap(),
         width: info.width.into(),
@@ -152,7 +155,7 @@ fn init_logger(info: BiosFramebufferInfo) -> FrameBufferInfo {
         )
     };
 
-    bootloader_x86_64_common::init_logger(framebuffer, framebuffer_info);
+    bootloader_x86_64_common::init_logger(framebuffer, framebuffer_info, log_level);
 
     framebuffer_info
 }

diff --git a/common/src/lib.rs b/common/src/lib.rs
@@ -4,7 +4,7 @@
 
 use crate::legacy_memory_region::{LegacyFrameAllocator, LegacyMemoryRegion};
 use bootloader_api::{
-    config::Mapping,
+    config::{LevelFilter, Mapping},
     info::{FrameBuffer, FrameBufferInfo, MemoryRegion, TlsTemplate},
     BootInfo, BootloaderConfig,
 };
@@ -35,13 +35,24 @@ pub mod logger;
 const PAGE_SIZE: u64 = 4096;
 
 /// Initialize a text-based logger using the given pixel-based framebuffer as output.  
-pub fn init_logger(framebuffer: &'static mut [u8], info: FrameBufferInfo) {
+pub fn init_logger(framebuffer: &'static mut [u8], info: FrameBufferInfo, log_level: LevelFilter) {
     let logger = logger::LOGGER.get_or_init(move || logger::LockedLogger::new(framebuffer, info));
     log::set_logger(logger).expect("logger already set");
-    log::set_max_level(log::LevelFilter::Trace);
+    log::set_max_level(convert_level(log_level));
     log::info!("Framebuffer info: {:?}", info);
 }
 
+fn convert_level(level: LevelFilter) -> log::LevelFilter {
+    match level {
+        LevelFilter::Off => log::LevelFilter::Off,
+        LevelFilter::Error => log::LevelFilter::Error,
+        LevelFilter::Warn => log::LevelFilter::Warn,
+        LevelFilter::Info => log::LevelFilter::Info,
+        LevelFilter::Debug => log::LevelFilter::Debug,
+        LevelFilter::Trace => log::LevelFilter::Trace,
+    }
+}
+
 /// Required system information that should be queried from the BIOS or UEFI firmware.
 #[derive(Debug, Copy, Clone)]
 pub struct SystemInfo {

diff --git a/uefi/src/main.rs b/uefi/src/main.rs
@@ -420,7 +420,7 @@ fn init_logger(st: &SystemTable<Boot>, config: BootloaderConfig) -> Option<RawFr
 
     log::info!("UEFI boot");
 
-    bootloader_x86_64_common::init_logger(slice, info);
+    bootloader_x86_64_common::init_logger(slice, info, config.log_level);
 
     Some(RawFrameBufferInfo {
         addr: PhysAddr::new(framebuffer.as_mut_ptr() as u64),