xc-llm-ascend/docs/source/developer_guide/versioning_policy.md

Versioning policy

Starting with vLLM 0.7.x, the vLLM Ascend Plugin (vllm-project/vllm-ascend) project follows the PEP 440 to publish matching with vLLM (vllm-project/vllm).

vLLM Ascend Plugin versions

Each vllm-ascend release will be versioned: v[major].[minor].[micro][rcN][.postN] (such as v0.7.3rc1, v0.7.3, v0.7.3.post1)

• Final releases: will typically be released every 3 months, will take the vLLM upstream release plan and Ascend software product release plan into comprehensive consideration.
• Pre releases: will typically be released on demand, ending with rcN, represents the Nth release candidate version, to support early testing by our users prior to a final release.
• Post releases: will typically be released on demand to support to address minor errors in a final release. It's different from PEP-440 post release note suggestion, it will contain actual bug fixes considering that the final release version should be matched strictly with the vLLM final release version (v[major].[minor].[micro]). The post version has to be published as a patch version of the final release.

For example:

• v0.7.x: it's the first final release to match the vLLM v0.7.x version.
• v0.7.3rc1: will be the first pre version of vllm-ascend.
• v0.7.3.post1: will be the post release if the v0.7.3 release has some minor errors.

Branch policy

vllm-ascend has main branch and dev branch.

• main: main branch，corresponds to the vLLM main branch and latest 1 or 2 release version. It is continuously monitored for quality through Ascend CI.
• vX.Y.Z-dev: development branch, created with part of new releases of vLLM. For example, v0.7.3-dev is the dev branch for vLLM v0.7.3 version.

Usually, a commit should be ONLY first merged in the main branch, and then backported to the dev branch to reduce maintenance costs as much as possible.

Maintenance branch and EOL:

The branch status will be in one of the following states:

Branch	Time frame	Summary
Maintained	Approximately 2-3 minor versions	All bugfixes are appropriate. Releases produced, CI commitment.
Unmaintained	Community interest driven	All bugfixes are appropriate. No Releases produced, No CI commitment
End of Life (EOL)	N/A	Branch no longer accepting changes

Branch state

Note that vllm-ascend will only be released for a certain vLLM release version rather than all versions. Hence, You might see only part of versions have dev branches (such as only 0.7.1-dev / 0.7.3-dev but no 0.7.2-dev), this is as expected.

Usually, each minor version of vLLM (such as 0.7) will correspond to a vllm-ascend version branch and support its latest version (for example, we plan to support version 0.7.3) as following shown:

Branch	Status	Note
main	Maintained	CI commitment for vLLM main branch and vLLM 0.8.x branch
v0.7.3-dev	Maintained	CI commitment for vLLM 0.7.3 version
v0.7.1-dev	Unmaintained	Replaced by v0.7.3-dev

Backward compatibility

For main branch, vllm-ascend should works with vLLM main branch and latest 1 or 2 release version. So to ensure the backward compatibility, we will do the following:

• Both main branch and target vLLM release is tested by Ascend E2E CI. For example, currently, vLLM main branch and vLLM 0.8.4 are tested now.
• For code changes, we will make sure that the changes are compatible with the latest 1 or 2 vLLM release version as well. In this case, vllm-ascend introduced a version check machinism inner the code. It'll check the version of installed vLLM pacakge first to decide which code logic to use. If users hit the InvalidVersion error, it sometimes means that they have installed an dev/editable version of vLLM package. In this case, we provide the env variable VLLM_VERSION to let users specify the version of vLLM package to use.
• For documentation changes, we will make sure that the changes are compatible with the latest 1 or 2 vLLM release version as well. Note should be added if there are any breaking changes.

Document Branch Policy

To reduce maintenance costs, all branch documentation content should remain consistent, and version differences can be controlled via variables in docs/source/conf.py. While this is not a simple task, it is a principle we should strive to follow.

Version	Purpose	Code Branch
latest	Doc for the latest dev branch	vX.Y.Z-dev (Will be main after the first final release)
version	Doc for historical released versions	Git tags, like vX.Y.Z[rcN]
stable（not yet released）	Doc for latest final release branch	Will be vX.Y.Z-dev after the first official release

As shown above:

• latest documentation: Matches the current maintenance branch vX.Y.Z-dev (Will be main after the first final release). Continuously updated to ensure usability for the latest release.
• version documentation: Corresponds to specific released versions (e.g., v0.7.3, v0.7.3rc1). No further updates after release.
• stable documentation (not yet released): Official release documentation. Updates are allowed in real-time after release, typically based on vX.Y.Z-dev. Once stable documentation is available, non-stable versions should display a header warning: You are viewing the latest developer preview docs. Click here to view docs for the latest stable release..

Software Dependency Management

• torch-npu: Ascend Extension for PyTorch (torch-npu) releases a stable version to PyPi every 3 months, a development version (aka the POC version) every month, and a nightly version every day. The PyPi stable version CAN be used in vLLM Ascend final version, the monthly dev version ONLY CANN be used in vLLM Ascend RC version for rapid iteration, the nightly version CANNOT be used in vLLM Ascend any version and branches.

Release Compatibility Matrix

Following is the Release Compatibility Matrix for vLLM Ascend Plugin:

vllm-ascend	vLLM	Python	Stable CANN	PyTorch/torch_npu
v0.8.5rc1	v0.8.5.post1	>= 3.9, < 3.12	8.1.RC1	2.5.1 / 2.5.1
v0.8.4rc2	v0.8.4	>= 3.9, < 3.12	8.0.0	2.5.1 / 2.5.1
v0.8.4rc1	v0.8.4	>= 3.9, < 3.12	8.0.0	2.5.1 / 2.5.1.dev20250320
v0.7.3rc2	v0.7.3	>= 3.9, < 3.12	8.0.0	2.5.1 / 2.5.1.dev20250320
v0.7.3rc1	v0.7.3	>= 3.9, < 3.12	8.0.0	2.5.1 / 2.5.1.dev20250308
v0.7.1rc1	v0.7.1	>= 3.9, < 3.12	8.0.0	2.5.1 / 2.5.1.dev20250218

Release cadence

release window

Date	Event
Early of 2025.05	v0.7.x Final release, v0.7.3
2025.05.06	Release candidates, v0.8.5rc1
2025.04.28	Release candidates, v0.8.4rc2
2025.04.18	Release candidates, v0.8.4rc1
2025.03.28	Release candidates, v0.7.3rc2
2025.03.14	Release candidates, v0.7.3rc1
2025.02.19	Release candidates, v0.7.1rc1