Struct AMXTimingSource 

pub struct AMXTimingSource {
    pub config: AMXTimingConfig,
}

Harvests timing jitter from the AMX (Apple Matrix eXtensions) coprocessor.

What it measures

Nanosecond timing of SGEMM (single-precision matrix multiply) dispatches to the AMX coprocessor via the Accelerate framework’s cblas_sgemm.

Why it’s entropic

The AMX is a dedicated coprocessor on the Apple Silicon die with its own register file, pipeline, and memory paths. Its timing depends on:

• Pipeline occupancy from ALL prior AMX operations (every process)
• Memory bandwidth contention on the unified memory controller
• Power state transitions (idle → active ramp-up latency)
• SLC (System Level Cache) eviction patterns
• Thermal throttling affecting AMX frequency independently of CPU cores

What makes it unique

No prior work has used AMX coprocessor timing as an entropy source. The AMX is a completely independent execution domain from CPU cores, providing entropy that is uncorrelated with CPU-based timing sources.

Configuration

See AMXTimingConfig for tunable parameters. Key options:

• von_neumann_debias: fixes severe LSB bias (recommended: true)
• interleave_memory_ops: disrupts pipeline steady-state
• matrix_sizes: controls which AMX pipeline configurations are exercised

Fields

config: AMXTimingConfig

Source configuration. Use Default::default() for recommended settings.

Trait Implementations

impl Default for AMXTimingSource

fn default() -> AMXTimingSource

Returns the “default value” for a type.

impl EntropySource for AMXTimingSource

fn info(&self) -> &SourceInfo

Source metadata.

fn is_available(&self) -> bool

Check if this source can operate on the current machine.

fn collect(&self, n_samples: usize) -> Vec<u8>

Collect raw entropy samples. Returns a Vec<u8> of up to n_samples bytes.

fn name(&self) -> &'static str

Convenience: name from info.