Memory safety notes
Arm MTE in practice
How allocation tags and fault handling affect the memory-protection boundary.
Background & research notes · AGIACC
Technical note. This is a mechanism overview, not a claim about AGIACC hardware support.
Tags and fault modes#
Arm’s Memory Tagging Extension associates allocation tags with memory granules and compares them with a logical tag on an access. On AArch64 Linux, the documented mechanism uses four-bit tags and 16-byte granules. Configuration determines whether mismatches are ignored, reported synchronously, or reported asynchronously; asymmetric handling is also available. See the Linux MTE documentation.
Limits shape deployment#
Tag collisions and granularity limit which errors are detected. The allocator, kernel, and application configuration determine coverage, and delayed fault reporting affects diagnosis and recovery. A tag match is not authorization for a business operation.
For an AI runtime, relevant questions include whether native libraries use tagged allocations, how a worker is terminated after a fault, and whether another component retains shared mutable state. Measure fault behavior and workload cost before selecting a deployment mode.
Next: Capability-based protection.