Remove the shim kernel crate

kernel/src/syscall/alarm.rs

@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use core::time::Duration;
+
+use super::SyscallReturn;
+use crate::{prelude::*, time::timer::Timeout};
+
+pub fn sys_alarm(seconds: u32, ctx: &Context) -> Result<SyscallReturn> {
+    debug!("seconds = {}", seconds);
+
+    let alarm_timer = ctx.process.timer_manager().alarm_timer();
+
+    let remaining = alarm_timer.remain();
+    let mut remaining_secs = remaining.as_secs();
+    if remaining.subsec_nanos() > 0 {
+        remaining_secs += 1;
+    }
+
+    if seconds == 0 {
+        // Clear previous timer
+        alarm_timer.cancel();
+        return Ok(SyscallReturn::Return(remaining_secs as _));
+    }
+
+    alarm_timer.set_timeout(Timeout::After(Duration::from_secs(seconds as u64)));
+
+    Ok(SyscallReturn::Return(remaining_secs as _))
+}