feat: scope stable abi to backend by drbh · Pull Request #682 · huggingface/kernels

drbh · 2026-06-30T15:59:30Z

this is a work in progress PR that scopes torches stable abi to individual back ends rather than having it be a global attribute.

HuggingFaceDocBuilderDev · 2026-06-30T16:01:18Z

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

github-actions · 2026-06-30T20:26:41Z

Coverage report — `kernels/`

Measured on: Python 3.10 / Torch 2.12.0.
Other CI configurations are not included in this number.
Hardware-gated code paths (ROCm/XPU/NPU/Darwin/Windows) are excluded or unreachable on the Linux+CUDA runner.

Total coverage: 84.6% — threshold: 80% — ✅

Per-file breakdown

Name	Stmts	Miss	Cover	Missing
src/kernels/__init__.py	10	0	100%
src/kernels/_system.py	6	1	83%	10
src/kernels/_versions.py	63	7	89%	46, 49, 52-53, 56-57, 100
src/kernels/backends.py	194	55	72%	40, 44, 48-51, 68, 90, 108, 117, 121, 125-127, 148, 170, 181, 188-191, 201, 205-225, 233, 256-276
src/kernels/compat.py	8	1	88%	5
src/kernels/deps.py	54	4	93%	58-59, 95, 98
src/kernels/layer/__init__.py	6	0	100%
src/kernels/layer/_interval_tree.py	103	4	96%	23, 52, 147, 150
src/kernels/layer/device.py	48	14	71%	42, 47-49, 91, 96-98, 101, 149, 152, 155-157
src/kernels/layer/func.py	81	7	91%	81, 111, 183, 301, 307, 320, 338
src/kernels/layer/globals.py	5	0	100%
src/kernels/layer/kernelize.py	74	8	89%	255, 281, 289-290, 296, 300, 316-318
src/kernels/layer/layer.py	210	16	92%	167, 210, 216, 229, 337, 417-418, 430, 439, 447, 458, 487, 491, 504, 557, 587
src/kernels/layer/mode.py	14	0	100%
src/kernels/layer/repos.py	130	34	74%	27, 33, 36-41, 61-62, 68, 71-74, 88, 92, 101-102, 108, 111-114, 121-122, 128, 131-134, 141-142, 148, 151-154, 235
src/kernels/lockfile.py	71	46	35%	37-104, 108-131
src/kernels/status.py	49	2	96%	23, 81
src/kernels/utils.py	301	55	82%	65, 77-81, 87-88, 218, 222, 225, 287, 295, 334-335, 373, 404, 409, 444, 673, 676, 678, 684, 697-698, 719-731, 735-742, 750, 754-764, 768-775, 813, 817, 836, 838
src/kernels/variants.py	262	19	93%	56, 87, 108, 138, 247-248, 289, 291, 371-378, 384-390, 421-427, 439-445, 534-536
src/kernels/verify.py	88	1	99%	32
TOTAL	1777	274	85%

Updated by the Test kernels workflow on commit c4a0e0d0688190f0e515b34e01e8936cecd7f861.

danieldk · 2026-07-01T08:41:15Z

+/// Validate that a per-backend `[torch.stable-abi]` mapping only references
+/// backends that are declared in `[general].backends`.
+fn validate_stable_abi(build: &CurrentConfig) -> Result<()> {
+    let v4::Framework::Torch(torch) = &build.framework else {


I know this is still in draft, but vN should not spread across the code base. This validation should probably be in the v4 file itself in the deserialization of Build (since that holds both General and Framework).

Though I'm not 100% sure if this is worth validating. It's nice to be able to remove a backend from the list for quick testing without removing every other occurrence of that backend in build.toml.

Co-authored-by: Daniël de Kok <me@danieldk.eu>

danieldk · 2026-07-02T08:13:14Z

+pub enum TorchAbi {
+    All(Version),
+    Mapping(BTreeMap<Backend, Version>),
+}


Pasted from Slack to have it in the review:

I thought a bit more about the extended Stable ABI mapping. Let's do this:

• Make v5 of the Build format. In v4 it stays String, in v5 we make it the mapping.
• Conversion from v4 to v5 is simple: when stable-abi is set, enumerate over the backends and set the stable ABI for the available backends..
• If we make v5, we should add edition to general and make it mandatory to set edition = 5. In this way we can start to unambiguously parse different versions in the future..
• If we don't detect edition, ask the user to run kernel-builder update-build (or maybe auto-update from v4 to v5, not on disk, but just in the builder, so that it works without running update-build).

By doing this, we avoid a lot of conditionals that check whether stable-abi is a string or mapping/attrset.

What do you think?

these are great recommendations

added v5 in latest changes with edition field and expects a mapping for stable abi

added logic to upgrade v4 to v5 in memory so existing stable-abi="string" should work without issues

updated update-builder to target updating to v5

these changes also include config changes to all of the examples so there are many more files changed in latest but most are one line additions to configs

drbh · 2026-07-02T20:58:16Z

this kernel community PR uses this branch to validate the new version/scoped stable abi builds

feat: activation stable abi kernels-community#1007

danieldk

Looks great!

One question about a CMake change, plus a suggestion to hardcode the version in the v5 General.

danieldk · 2026-07-03T10:52:48Z

  add_compile_definitions(CUDA_KERNEL)
 elseif(GPU_LANG STREQUAL "HIP")
-  if(NOT HIP_FOUND)
+  if(NOT HIP_FOUND AND NOT PYTORCH_FOUND_HIP)


Why is this additional condition needed? Seems to make it less strict?

I ran into a build issue with rocm which seems related to torch 2.13. It seems like they no longer expose HIP_FOUND and now expose PYTORCH_FOUND_HIP only

build issue:
https://github.com/huggingface/kernels-community/actions/runs/28620863071/job/84876068475

pr with changes to HIP_FOUND
pytorch/pytorch@d921fd0

HIP_FOUND is not longer found in the codebase when searching on main

I opt'ed to adding PYTORCH_FOUND_HIP instead of replacing in order to avoid any regressions with older torch versions, this way we will only throw if both HIP_FOUND and PYTORCH_FOUND_HIP are false

danieldk · 2026-07-03T10:55:20Z

+        let edition = EditionProbe::deserialize(value.clone())
+            .map_err(|err| de::Error::custom(format!("invalid `general.edition`: {err}")))?
+            .general
+            .and_then(|general| general.edition);
+
+        match edition {
+            // Configs with editions
+            Some(5) => v5::Build::deserialize(value)
+                .map(BuildCompat::V5)
+                .map_err(de::Error::custom),
+


danieldk · 2026-07-03T10:58:50Z

+    pub version: usize,
+
+    /// Build format edition. Must be `5` for this schema.
+    pub edition: usize,


Would be nice to hard-set this to 5. The serde author has a crate for this:

https://crates.io/crates/monostate

ah nice improvement, I've added in the latest commits.

drbh mentioned this pull request Jun 30, 2026

feat: activation stable abi huggingface/kernels-community#1007

Open

danieldk reviewed Jul 1, 2026

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Comment thread nix-builder/lib/kernel-config.nix Outdated

drbh temporarily deployed to testpypi July 1, 2026 16:09 — with GitHub Actions Inactive

drbh temporarily deployed to testpypi July 1, 2026 16:10 — with GitHub Actions Inactive

drbh and others added 3 commits July 1, 2026 12:11

feat: scope stable abi to backend

44ed59d

fix: remove unneeded validation

1f66a81

Update nix-builder/lib/kernel-config.nix

defa006

Co-authored-by: Daniël de Kok <me@danieldk.eu>

drbh force-pushed the backend-scoped-stable-abi branch from 0633fd1 to defa006 Compare July 1, 2026 16:11

drbh temporarily deployed to testpypi July 1, 2026 16:11 — with GitHub Actions Inactive

fix: format nix

351ae9e

drbh temporarily deployed to testpypi July 1, 2026 16:16 — with GitHub Actions Inactive

fix: remove unneeded tests

a1de83d

drbh temporarily deployed to testpypi July 1, 2026 16:59 — with GitHub Actions Inactive

fix: add note to docs

4666e19

drbh temporarily deployed to testpypi July 1, 2026 17:15 — with GitHub Actions Inactive

drbh marked this pull request as ready for review July 1, 2026 20:46

danieldk reviewed Jul 2, 2026

View reviewed changes

fix: add v5 with edition

2301259

drbh temporarily deployed to testpypi July 2, 2026 19:50 — with GitHub Actions Inactive

fix: refactor cleanups

2ce83fc

drbh temporarily deployed to testpypi July 2, 2026 20:10 — with GitHub Actions Inactive

feat: bump examples and docs

c5aed99

drbh temporarily deployed to testpypi July 2, 2026 20:23 — with GitHub Actions Inactive

fix: tweak for hip on 2.13

c3e3447

drbh temporarily deployed to testpypi July 2, 2026 21:14 — with GitHub Actions Inactive

danieldk reviewed Jul 3, 2026

View reviewed changes

feat: prefer monostate for edition checking

c4a0e0d

drbh temporarily deployed to testpypi July 3, 2026 16:12 — with GitHub Actions Inactive

danieldk approved these changes Jul 3, 2026

View reviewed changes

drbh merged commit 8c4761c into main Jul 3, 2026
51 of 55 checks passed

danieldk deleted the backend-scoped-stable-abi branch July 3, 2026 16:34

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