feat(kernel): console cap gates DebugPutchar, no uart fast path; spawn start arg in a0; delegate returns slot

crates/init/src/devices.rs

@@ -62,6 +62,15 @@ pub fn system_control() -> Option<CapSlot> {
     slot(info.system_control_slot)
 }
 
+/// The console capability, until init hands it to the log server.
+pub fn console() -> Option<CapSlot> {
+    let info = boot_info();
+    if info.magic != types::bootinfo::MAGIC {
+        return None;
+    }
+    slot(info.console_slot)
+}
+
 /// Sorts the board's devices out.
 pub fn discover() -> Devices {
     let info = boot_info();

crates/init/src/lib.rs

@@ -111,6 +111,7 @@ const SERVERS: &[ServerInfo] = &[
 ];
 
 pub fn run() -> ! {
+    libkos::start::set_console(devices::console());
     libkos::println!("init: started (pid={:#x})", syscall::get_process_id().raw());
 
     // Drivers wait for their device before serving, so this comes first:
@@ -151,7 +152,7 @@ pub fn run() -> ! {
 
         if let Some(ep_cap) = syscall::create_endpoint() {
             syscall::delegate(ep_cap, loaded.process_cap, ipc_perms);
-            syscall::spawn_thread_in(loaded.process_cap, loaded.entry_point, USER_STACK_TOP);
+            start(&loaded, true);
         }
 
         libkos::println!("ok (entry={:#x})", loaded.entry_point.raw());
@@ -171,7 +172,7 @@ pub fn run() -> ! {
         let client = PermissionSet::empty().with(Permission::Execute);
         syscall::delegate(INPUT_EP, snake.process_cap, client);
         syscall::delegate(DISPLAY_EP, snake.process_cap, client);
-        syscall::spawn_thread_in(snake.process_cap, snake.entry_point, USER_STACK_TOP);
+        start(&snake, false);
         libkos::println!("ok");
     } else {
         libkos::println!("SKIP");
@@ -182,6 +183,16 @@ pub fn run() -> ! {
     idle();
 }
 
+/// Starts `program`, lending it init's console if `console`.
+pub(crate) fn start(program: &LoadedProcess, console: bool) {
+    let write = PermissionSet::empty().with(Permission::Write);
+    let slot = libkos::start::console()
+        .filter(|_| console)
+        .and_then(|c| syscall::delegate(c, program.process_cap, write));
+    let arg = types::start_arg::encode(slot, None);
+    syscall::spawn_thread_in(program.process_cap, program.entry_point, USER_STACK_TOP, arg);
+}
+
 /// A region of init's own to read program files into.
 fn scratch() -> Option<&'static mut [u8]> {
     let region = syscall::create_region(PageCount::new(SCRATCH_PAGES)?).ok()?;

crates/init/src/selftest.rs

@@ -45,10 +45,11 @@ fn start_spinner(storage: &mut Storage, scratch: &mut [u8], page: CapSlot) -> Re
         .with(Permission::Read)
         .with(Permission::Write)
         .with(Permission::Delegate);
-    if !syscall::delegate(page, spinner.process_cap, rw) {
+    // The page first: the spinner expects it in slot 0.
+    if syscall::delegate(page, spinner.process_cap, rw).is_none() {
         return Err("cannot give the spinner its page");
     }
-    syscall::spawn_thread_in(spinner.process_cap, spinner.entry_point, crate::USER_STACK_TOP);
+    crate::start(&spinner, true);
     if !wait_until(3000, || counters().iter().all(|c| *c > 0)) {
         return Err("spinner threads did not all start");
     }