1 files changed, 66 insertions, 0 deletions
diff --git a/library/std/src/sys/thread/uefi.rs b/library/std/src/sys/thread/uefi.rs
new file mode 100644
index 00000000000..47a48008c76
--- /dev/null
+++ b/library/std/src/sys/thread/uefi.rs
@@ -0,0 +1,66 @@
+use super::unsupported;
+use crate::ffi::CStr;
+use crate::io;
+use crate::num::NonZero;
+use crate::ptr::NonNull;
+use crate::time::{Duration, Instant};
+
+pub struct Thread(!);
+
+pub const DEFAULT_MIN_STACK_SIZE: usize = 64 * 1024;
+
+impl Thread {
+    // unsafe: see thread::Builder::spawn_unchecked for safety requirements
+    pub unsafe fn new(
+        _stack: usize,
+        _name: Option<&str>,
+        _p: Box<dyn FnOnce()>,
+    ) -> io::Result<Thread> {
+        unsupported()
+    }
+
+    pub fn yield_now() {
+        // do nothing
+    }
+
+    pub fn set_name(_name: &CStr) {
+        // nope
+    }
+
+    pub fn sleep(dur: Duration) {
+        let boot_services: NonNull<r_efi::efi::BootServices> =
+            crate::os::uefi::env::boot_services().expect("can't sleep").cast();
+        let mut dur_ms = dur.as_micros();
+        // ceil up to the nearest microsecond
+        if dur.subsec_nanos() % 1000 > 0 {
+            dur_ms += 1;
+        }
+
+        while dur_ms > 0 {
+            let ms = crate::cmp::min(dur_ms, usize::MAX as u128);
+            let _ = unsafe { ((*boot_services.as_ptr()).stall)(ms as usize) };
+            dur_ms -= ms;
+        }
+    }
+
+    pub fn sleep_until(deadline: Instant) {
+        let now = Instant::now();
+
+        if let Some(delay) = deadline.checked_duration_since(now) {
+            Self::sleep(delay);
+        }
+    }
+
+    pub fn join(self) {
+        self.0
+    }
+}
+
+pub(crate) fn current_os_id() -> Option<u64> {
+    None
+}
+
+pub fn available_parallelism() -> io::Result<NonZero<usize>> {
+    // UEFI is single threaded
+    Ok(NonZero::new(1).unwrap())
+}