1.20.1-rc1 (March 18, 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:
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