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Author SHA1 Message Date
Naitik Pal
cf912cbd88
feat(studio): add UNSLOTH_LLAMA_CPP_BACKEND env var to force CPU fallback #7213 (#7228)
* test(studio): add e2e test for cpu-fallback overriding vulkan

* feat(studio): add UNSLOTH_LLAMA_CPP_BACKEND env var

* feat(studio): add UNSLOTH_LLAMA_CPP_BACKEND env var

* Preserve UNSLOTH_LLAMA_CPP_BACKEND=cpu across llama.cpp updates for PR #7228

The in-app updater rebuilt the installer command without --cpu-fallback and
only re-asserted Vulkan, so accepting a llama.cpp update after forcing CPU on
an Intel iGPU host re-ran host detection and routed back to the crashing Vulkan
bundle (#7213). Record install_kind in the prebuilt marker and re-assert
--cpu-fallback on update when the installed bundle is CPU.

Also make setup.sh's UNSLOTH_LLAMA_CPP_BACKEND check case-insensitive to match
setup.ps1, and add tests for the updater CPU preservation and the setup.sh flag
plumbing.

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Trim and validate UNSLOTH_LLAMA_CPP_BACKEND, warn on unknown values for PR #7228

Trim surrounding whitespace and lowercase the value in both setup.sh and
setup.ps1, so values like ' cpu ' or 'CPU' still force the CPU-only prebuilt.
An unrecognized value (e.g. 'gpu') now prints a warning instead of silently
falling back to auto. Extend test_setup_llama_cpp_backend.py to cover both
scripts, including trimmed, empty and unknown values.

* Preserve arm64 CPU installs on update and honor CPU override in Windows prune for PR #7228

The update-path CPU preservation only matched install_kind ending in -cpu, so
arm64 CPU bundles (linux-arm64, windows-arm64) were re-routed to a GPU or source
build on update. Match the full set of CPU-only kinds instead.

Persisting install_kind also activated the previously inert Windows
mismatch-prune in setup.ps1: on a GPU host with UNSLOTH_LLAMA_CPP_BACKEND=cpu it
saw the windows-cpu marker as mismatched and deleted it every rerun. Normalize
the override once and make CPU expected so a deliberate CPU install is kept.
Extend the tests to cover both.

* Document legacy llama.cpp markers keep heal-to-GPU on update for PR #7228

Legacy prebuilt markers written before install_kind was persisted intentionally
do not force --cpu-fallback on update: the in-app updater lets them re-resolve
(heal to a GPU bundle) per the existing behavior from #6097, and only markers
that explicitly record a CPU install_kind are pinned to CPU. Add a comment and a
regression case documenting the boundary.

* Tighten llama.cpp CPU-fallback comments for PR #7228

* Fix Windows install-prune to keep valid Intel/fallback bundles for PR #7228

Persisting install_kind activated the setup.ps1 mismatch-prune, whose
expectedKinds was incomplete: the non-NVIDIA/non-AMD branch omitted
windows-vulkan (the Intel auto-route) and the GPU branches omitted the
windows-cpu/windows-arm64 fallback the installer uses when a GPU prebuilt is
missing. That made every setup rerun delete and re-download a valid Intel Vulkan
(or CPU-fallback) install. List all kinds the installer can produce per host so
only a bundle the host cannot run is pruned. Cover the full matrix in tests.

* Persist force_cpu marker flag so only forced CPU installs re-assert on update for PR #7228

* Add --force-cpu for deliberate CPU installs and warn on macOS for PR #7228

* Record force_cpu when reusing a matching CPU bundle for PR #7228

* Accept force_cpu keyword in installer test validator fakes for PR #7228

---------

Co-authored-by: danielhanchen <unslothai@gmail.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Daniel Han <danielhanchen@gmail.com>
2026-07-20 00:33:56 -07:00