This document is relevant for: Inf1, Inf2, Trn1, Trn2, Trn3

AWS Neuron SDK 2.27.0: Neuron Kernel Interface (NKI) release notes

Date of release: December 19, 2025

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What’s New

This release introduces NKI Beta 2, featuring the new NKI Compiler and significant enhancements to the NKI language constructs and APIs, including changes to existing APIs. For information about the different NKI Beta versions, see About NKI Beta Versions.

To take advantage of Beta 2 with the new compiler, import the nki.* namespace in your code and annotate your top-level kernel function with @nki.jit.

Backward Compatibility and Migration

Neuron 2.27 supports both the neuronxcc.nki.* and nki.* namespaces side by side, allowing existing Beta 1 kernels to continue working seamlessly. However, Neuron 2.27 will be the last release to include support for the neuronxcc.nki.* namespace. Starting with Neuron 2.28, this namespace will no longer be supported.

The new nki.* namespace introduces changes to NKI APIs and language constructs. We encourage customers to migrate existing kernels from neuronxcc.nki.* to the new nki.* namespace. A kernel migration guide is available in the Neuron 2.27 documentation to assist with this transition.

New nki.language APIs

• nki.language.device_print

New nki.isa APIs

• nki.isa.dma_compute

• nki.isa.quantize_mx

• nki.isa.nc_matmul

• nki.isa.nc_n_gather [used to be nl.gather_flattened with free partition limited to 512]

• nki.isa.rand2

• nki.isa.rand_set_state

• nki.isa.rand_get_state

• nki.isa.set_rng_seed

• nki.isa.rng

New dtypes

• nki.language.float8_e5m2_x4

• nki.language.float4_e2m1fn_x4

• nki.language.float8_e4m3fn_x4

Changes to Existing APIs

• Several nki.language APIs have been removed in NKI Beta 2

• All nki.isa APIs have dst as an input param

• All nki.isa APIs removed dtype and mask support

• nki.isa.memset — removed shape positional arg , since we have dst

• nki.isa.affine_select — instead of pred, we now take pattern and cmp_op params

• nki.isa.iota — expr replaced with pattern and offset

• nki.isa.nc_stream_shuffle - src and dst order changed

Documentation Updates

• Restructured NKI Documentation to align with workflows

• Added Trainium3 Architecture Guide for NKI

• Added About Neuron Kernel Interface (NKI)

• Added NKI Environment Setup Guide

• Added Get Started with NKI

• Added NKI Language Guide

• Added About the NKI Compiler

• Added About NKI Beta Versions

• Added MXFP Matrix Multiplication with NKI

• Updated Matrix Multiplication Tutorial

• Updated Profile a NKI Kernel

• Updated NKI APIs

• Updated NKI Library docs

• Removed NKI Error Guide

Known issues

• nki.isa.nc_matmul - is_moving_onezero was incorrectly named is_moving_zero in this release

• NKI ISA semantic checks are not available with Beta 2, workaround is to reference the API docs

• NKI Collectives are not available with Beta 2

• nki.benchmark and nki.profile are not available

This document is relevant for: Inf1, Inf2, Trn1, Trn2, Trn3