---
id: pr-flashinfer-1363
repo: flashinfer-ai/flashinfer
pr: 1363
title: Support scale factor start index for fp4 mha prefill/decode
author: weireweire
date: '2025-08-03'
url: https://github.com/flashinfer-ai/flashinfer/pull/1363
source_category: upstream-code
architectures:
- sm100
tags:
- decode
- flash-attention
- fp4
- prefill
techniques: []
hardware_features:
- fp4
kernel_types:
- decode
- flash-attention
- prefill
languages:
- cuda-cpp
captured_at: '2026-04-27'
status: merged
merge_sha: 50dcd9ac9472b3ebc0eb155d003a2bef6ba34dc2
inclusion_reason: kernel file changes
changed_paths:
- csrc/trtllm_fmha_kernel_launcher.cu
- flashinfer/decode.py
- flashinfer/prefill.py
- flashinfer/utils.py
- tests/test_trtllm_gen_context.py
- tests/test_trtllm_gen_decode.py
- tests/utils_fp4.py
head_ref_oid: aea5ed9108237d19e7d15fe1f1908e8fcc64b89d
artifact_dir: evidence/pull-bundles/flashinfer/gh-1363
---
# Support scale factor start index for fp4 mha prefill/decode

- Repository: `flashinfer-ai/flashinfer`
- PR: [1363](https://github.com/flashinfer-ai/flashinfer/pull/1363)
- Decision: `kernel file changes`
- Reason: kernel file changes

## Changed Paths

- `csrc/trtllm_fmha_kernel_launcher.cu`
- `flashinfer/decode.py`
- `flashinfer/prefill.py`
- `flashinfer/utils.py`
- `tests/test_trtllm_gen_context.py`
- `tests/test_trtllm_gen_decode.py`
- `tests/utils_fp4.py`

## Evidence Bundle

`evidence/pull-bundles/flashinfer/gh-1363`
