sync fa4 and add smoke tests.

[sayakpaul]

Since it's a no-arch kernel, didn't bump the version (need to fix the checker; separate PR).

[sayakpaul]

/kernel-bot build flash-attn4

[github-actions]

Build request processed.

Command: /kernel-bot build flash-attn4
Mode: build only
Target branch: pr-1147
PR head SHA: 49e0aa8579102c79527086cb8edd7c1c90f8215d
Workflows: build.yaml, build-mac.yaml, build-windows.yaml

Dispatched (1):

• flash-attn4 (build.yaml): https://github.com/huggingface/kernels-community/actions/runs/34604977289

[sayakpaul]

/kernel-bot build flash-attn4

[github-actions]

Build request processed.

Command: /kernel-bot build flash-attn4
Mode: build only
Target branch: pr-1147
PR head SHA: 2ad88394ddf674c7646787a3ecd881ae27e60e69
Workflows: build.yaml, build-mac.yaml, build-windows.yaml

Dispatched (1):

• flash-attn4 (build.yaml): https://github.com/huggingface/kernels-community/actions/runs/34678748898

[sayakpaul]

/kernel-bot build flash-attn4

[github-actions]

Build request processed.

Command: /kernel-bot build flash-attn4
Mode: build only
Target branch: pr-1147
PR head SHA: f6e8b7db0e030480e9aa0c9cfa6283c581dd45b1
Workflows: build.yaml, build-mac.yaml, build-windows.yaml

Dispatched (1):

• flash-attn4 (build.yaml): https://github.com/huggingface/kernels-community/actions/runs/34891099484

[sayakpaul]

@danieldk addressed the feedback. The public check API needs a bit more work which I will do in a separate PR (followed by an update in the instructions to bump version for no-arch kernels).

[danieldk]

Added two more small comments

[sayakpaul]

/kernel-bot build flash-attn4

[github-actions]

Build request processed.

Command: /kernel-bot build flash-attn4
Mode: build only
Target branch: pr-1147
PR head SHA: 4a67a0d46d5d6cddaf473e206eb6e27ea967eee4
Workflows: build.yaml, build-mac.yaml, build-windows.yaml

Dispatched (1):

• flash-attn4 (build.yaml): https://github.com/huggingface/kernels-community/actions/runs/35219779582

[sayakpaul]

/kernel-bot build flash-attn4

[github-actions]

Build request processed.

Command: /kernel-bot build flash-attn4
Mode: build only
Target branch: pr-1147
PR head SHA: 20d5fc7a3dceb1a47d77b6995d0e9099e71af70e
Workflows: build.yaml, build-mac.yaml, build-windows.yaml

Dispatched (1):

• flash-attn4 (build.yaml): https://github.com/huggingface/kernels-community/actions/runs/35234062035

[sayakpaul]

@danieldk I think I have resolved all your comments. Regarding running the tests on Hopper and Blackwell, I did that too. Some tests didn't run because of environment problems and I didn't chase them further (but note that these are just 10ish in number).