1.91.1 xous arm changes

[badicsalex]

No description provided.

[Copilot]

Pull request overview

This PR modernizes the Xous platform implementation in Rust's standard library by migrating from custom synchronization primitives to futex-based implementations and upgrading timing APIs from millisecond to nanosecond precision.

• Migrates mutex, rwlock, once, and condvar implementations from custom Xous-specific code to futex-based primitives
• Updates all time-related APIs to use nanoseconds instead of milliseconds for improved precision
• Simplifies the allocator implementation by replacing a custom spinlock with std::sync::Mutex

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 15 comments.

Show a summary per file

File	Description
library/std/src/sys/thread/xous.rs	Converts sleep() to use nanoseconds with simplified single-call implementation
library/std/src/sys/sync/thread_parking/xous.rs	Complete rewrite using mutex/condvar instead of custom state machine
library/std/src/sys/sync/rwlock/mod.rs	Moves xous from queue-based to futex-based RwLock
library/std/src/sys/sync/once/mod.rs	Moves xous from queue-based to futex-based Once
library/std/src/sys/sync/mutex/xous.rs	Removes custom mutex implementation (entire file deleted)
library/std/src/sys/sync/mutex/mod.rs	Switches xous to use futex-based Mutex
library/std/src/sys/sync/condvar/xous.rs	Rewrites condvar with dual futex/ticktimer waiting support
library/std/src/sys/pal/xous/time.rs	Updates time APIs from milliseconds to nanoseconds
library/std/src/sys/pal/xous/mod.rs	Adds futex module export
library/std/src/sys/pal/xous/futex.rs	Introduces new futex wrapper implementation for xous
library/std/src/sys/alloc/xous.rs	Simplifies allocator by replacing custom lock with std::sync::Mutex
library/std/src/os/xous/services/ticktimer.rs	Updates ticktimer API enum variants to use nanosecond parameters

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[Copilot]

The import statement has a syntax error with an extra comma and missing type parameter. The Atomic type requires a type parameter (e.g., Atomic<usize>), and there's an unnecessary comma before the closing brace.

Suggested change

	use core::{sync::atomic::{Atomic}, time::Duration};
	use core::{sync::atomic::Atomic, time::Duration};

[Copilot]

Spelling error in assertion message: "Timeouts" should be "Timeout" (singular form is more appropriate here).

Suggested change

	assert!(timeout.is_none(), "Timeouts on xous futexes is not supported");
	assert!(timeout.is_none(), "Timeout on xous futexes is not supported");

[badicsalex]

I closed this accidentally.

[nicoburniske]

what is this? why do we have two of the same thing? is this something required to be exported from the futex file?

[nicoburniske]

approved