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amd: do not promise aarch64 a ROCm 4-bit backend it never gets

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This commit is contained in:
Daniel Han 2026-07-28 22:54:41 +00:00
commit 1de299c673
3 changed files with 65 additions and 2 deletions
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25
studio/install_python_stack.py
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@ -424,6 +424,16 @@ def _bnb_rocm_prerelease_url() -> str | None:
return _BNB_ROCM_PRERELEASE_URLS.get(arch)
def _bnb_rocm_arch_has_binary() -> bool:
"""False on aarch64: bitsandbytes ships no ROCm kernels there at any version.
The PyPI 0.50.0 and continuous-release_main aarch64 wheels both carry only
libbitsandbytes_cpu.so plus CUDA variants, so neither install path gives
aarch64 a 4-bit backend and neither message may claim one.
"""
arch = platform.machine().lower()
return {"amd64": "x86_64", "arm64": "aarch64"}.get(arch, arch) != "aarch64"
def _amd_smi_env() -> dict[str, str] | None:
"""On Windows, env with __COMPAT_LAYER=RunAsInvoker; None elsewhere.
NB: RunAsInvoker doesn't stop amd-smi's runtime elevation (its manifest is
@ -2021,10 +2031,15 @@ def _ensure_rocm_torch() -> None:
force_pip = True,
)
if not _bnb_installed:
_fallback_note = (
", which carries the ROCm 4-bit fix"
if _bnb_rocm_arch_has_binary()
else ""
)
print(
_red(
" bnb pre-release install failed; falling back to PyPI "
f"{_BNB_ROCM_PYPI_FALLBACK}, which carries the ROCm 4-bit fix"
f"{_BNB_ROCM_PYPI_FALLBACK}{_fallback_note}"
)
)
if not _bnb_installed:
@ -2036,6 +2051,14 @@ def _ensure_rocm_torch() -> None:
_BNB_ROCM_PYPI_FALLBACK,
constrain = False,
)
if not _bnb_rocm_arch_has_binary():
print(
_red(
" aarch64: bitsandbytes ships no ROCm kernels on this arch; "
"4-bit QLoRA needs a source build -- "
"https://docs.unsloth.ai/get-started/install-and-update/amd"
)
)
# _uv_safe_path is imported from backend.utils.uv_path_safety (shared with mlx_repair).