v1.20.1

1.20.1 (May 6, 2026)

Features:

RDMA CORE (IB, ROCE, etc.)

• Added 'auto' option for UCX_IB_MLX5_DEVX_OBJECTS which disables DevX when ODP is available (for Grace)
• Prioritize routes with longer subnet masks for improved reachability check accuracy

Documentation

• Clarified that user buffer can be modified after calling ucp_atomic_op_nbx

Bugfixes:

Build

• Fixed IB configuration const correctness for strchr() to allow compilation with GCC 15.2.1

UCP

• Increased TLS info buffer size in transport selection to prevent potential truncation
• Fixed incorrect warning about valid environment variable names
• Fixed ucp_config_modify not reporting an error when no matching modifiable configuration exists.

RDMA CORE (IB, ROCE, etc.)

• Fixed DevX objects flag handling
• Fixed device memory allocation alignment in MLX5 DevX
• Fixed IB memory handle flags enum order
• Disabled indirect atomic registration for Direct NIC
• Fixed stale destination endpoint ID and acks from before connection reset in UD transport
• Fix RoCE reachable route check when node_guuid is not unique among HCAs

CUDA

• Fixed CUDA context handling for system device during rkey unpack

ROCM

• Fixed HSA memory type check for newer ROCm releases

UCS

• Fixed rcache locking for GDR copy

Packaging

• Fix libnvidia-compute removal from ucx-cuda debian package dependencies, breaking existing installation
• Obsoleted KNEM sub-package
• Fix maintainer field in debian packaging