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Auto merge of rust-lang#120938 - Ayush1325:uefi-thread, r=joboet,Nils…
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…trieb

Implement sys/thread for UEFI

Since UEFI has no concept of threads, most of this module can be ignored. However, implementing parts that make sense.

- Implement sleep
- Implement available_parallelism
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bors committed Feb 13, 2024
2 parents d26b417 + af428db commit 09d73fa
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Showing 2 changed files with 60 additions and 1 deletion.
1 change: 0 additions & 1 deletion library/std/src/sys/pal/uefi/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,6 @@ pub mod pipe;
#[path = "../unsupported/process.rs"]
pub mod process;
pub mod stdio;
#[path = "../unsupported/thread.rs"]
pub mod thread;
#[path = "../unsupported/thread_local_key.rs"]
pub mod thread_local_key;
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60 changes: 60 additions & 0 deletions library/std/src/sys/pal/uefi/thread.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,60 @@
use super::unsupported;
use crate::ffi::CStr;
use crate::io;
use crate::num::NonZeroUsize;
use crate::ptr::NonNull;
use crate::time::Duration;

pub struct Thread(!);

pub const DEFAULT_MIN_STACK_SIZE: usize = 4096;

impl Thread {
// unsafe: see thread::Builder::spawn_unchecked for safety requirements
pub unsafe fn new(_stack: usize, _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 join(self) {
self.0
}
}

pub fn available_parallelism() -> io::Result<NonZeroUsize> {
// UEFI is single threaded
Ok(NonZeroUsize::new(1).unwrap())
}

pub mod guard {
pub type Guard = !;
pub unsafe fn current() -> Option<Guard> {
None
}
pub unsafe fn init() -> Option<Guard> {
None
}
}

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