feat(userspace): log server sole console holder; init boots from manifest; adapter loads only init+storage

crates/libkos/src/io.rs

@@ -4,8 +4,13 @@ struct Writer;
 
 impl fmt::Write for Writer {
     fn write_str(&mut self, s: &str) -> fmt::Result {
-        // Without a console capability, output goes nowhere.
-        if let Some(console) = crate::start::console() {
+        // The log server first; a process without either prints nothing.
+        // A call, not a send: the text is out before the caller goes on.
+        if let Some(log) = crate::start::log() {
+            for chunk in s.as_bytes().chunks(types::log::TEXT_BYTES) {
+                let _ = crate::syscall::call(log, types::log::text_words(chunk), None);
+            }
+        } else if let Some(console) = crate::start::console() {
             for &b in s.as_bytes() {
                 crate::syscall::debug_putchar(console, b);
             }

crates/libkos/src/start.rs

@@ -8,8 +8,9 @@ use types::start_arg;
 #[unsafe(no_mangle)]
 static LIBKOS_START_ARG: AtomicUsize = AtomicUsize::new(0);
 
-/// Overrides the start argument's console once set; `NONE` drops output.
+/// Override the start argument's slots once set; `NONE` means none.
 static CONSOLE: AtomicUsize = AtomicUsize::new(UNSET);
+static LOG: AtomicUsize = AtomicUsize::new(UNSET);
 const UNSET: usize = usize::MAX;
 const NONE: usize = usize::MAX - 1;
 
@@ -19,18 +20,31 @@ fn arg() -> usize {
 
 /// The console capability this process prints through, if any.
 pub fn console() -> Option<CapSlot> {
-    match CONSOLE.load(Ordering::Relaxed) {
-        UNSET => start_arg::console(arg()),
-        v => CapSlot::new(u8::try_from(v).ok()?),
-    }
+    read(&CONSOLE, start_arg::console)
 }
 
 /// For a process that gets its console some other way (init, from BootInfo).
 pub fn set_console(slot: Option<CapSlot>) {
-    CONSOLE.store(slot.map_or(NONE, |s| s.value() as usize), Ordering::Relaxed);
+    write(&CONSOLE, slot);
 }
 
-/// The log server endpoint this process was given, if any.
+/// The log server endpoint this process prints to, if any.
 pub fn log() -> Option<CapSlot> {
-    start_arg::log(arg())
+    read(&LOG, start_arg::log)
+}
+
+/// For a process given its log endpoint after it started.
+pub fn set_log(slot: Option<CapSlot>) {
+    write(&LOG, slot);
+}
+
+fn read(cell: &AtomicUsize, from_arg: fn(usize) -> Option<CapSlot>) -> Option<CapSlot> {
+    match cell.load(Ordering::Relaxed) {
+        UNSET => from_arg(arg()),
+        v => CapSlot::new(u8::try_from(v).ok()?),
+    }
+}
+
+fn write(cell: &AtomicUsize, slot: Option<CapSlot>) {
+    cell.store(slot.map_or(NONE, |s| s.value() as usize), Ordering::Relaxed);
 }