---
id: pr-vllm-38835
repo: vllm-project/vllm
pr: 38835
title: '[Attention] relax the head dim 512 and paged kv for sm90+FA4'
author: IwakuraRein
date: '2026-04-08'
url: https://github.com/vllm-project/vllm/pull/38835
source_category: upstream-code
architectures:
- sm100
- sm90
tags:
- attention
techniques: []
hardware_features: []
kernel_types:
- attention
languages:
- python
captured_at: '2026-04-17'
status: merged
merge_sha: e24e0a43a4f6138c8cf611f880c3609e3edf7624
inclusion_reason: kernel file changes
changed_paths:
- cmake/external_projects/vllm_flash_attn.cmake
- vllm/v1/attention/backends/fa_utils.py
- vllm/v1/attention/backends/flash_attn.py
- vllm/vllm_flash_attn/flash_attn_interface.py
head_ref_oid: ad526440279417eee5fabb07066e9fdbfc507f7b
artifact_dir: evidence/pull-bundles/vllm/gh-38835
---
# [Attention] relax the head dim 512 and paged kv for sm90+FA4

- Repository: `vllm-project/vllm`
- PR: [38835](https://github.com/vllm-project/vllm/pull/38835)
- Decision: `kernel file changes`
- Reason: kernel file changes

## Changed Paths

- `cmake/external_projects/vllm_flash_attn.cmake`
- `vllm/v1/attention/backends/fa_utils.py`
- `vllm/v1/attention/backends/flash_attn.py`
- `vllm/vllm_flash_attn/flash_attn_interface.py`

## Evidence Bundle

`evidence/pull-bundles/vllm/gh-38835`
