On an x86_64 machine, I’ve seen this: --8<---------------cut here---------------start------------->8--- $ guix build python-scanpy --no-grafts --check […] starting phase `check' ============================= test session starts ============================== platform linux -- Python 3.8.2, pytest-5.3.5, py-1.8.1, pluggy-0.13.1 rootdir: /tmp/guix-build-python-scanpy-1.7.2.drv-0/scanpy-1.7.2 plugins: hypothesis-5.4.1, cov-2.8.1, black-0.3.8 Fatal Python error: Illegal instruction Current thread 0x00007ffff785c300 (most recent call first): File "", line 219 in _call_with_frames_removed File "", line 1109 in exec_module File "", line 671 in _load_unlocked File "", line 975 in _find_and_load_unlocked File "", line 991 in _find_and_load File "", line 219 in _call_with_frames_removed File "", line 1042 in _handle_fromlist File "/gnu/store/368d0i579ga5sbc3mms4bg7bd4lzj6km-python-numcodecs-0.6.4/lib/python3.8/site-packages/numcodecs/__init __.py", line 45 in File "", line 219 in _call_with_frames_removed File "", line 783 in exec_module File "", line 671 in _load_unlocked File "", line 975 in _find_and_load_unlocked File "", line 991 in _find_and_load File "/gnu/store/cjclqalblsxf8l6cn1l1r4qmyjab0di3-python-zarr-2.4.0/lib/python3.8/site-packages/zarr/codecs.py", line 3 in File "", line 219 in _call_with_frames_removed File "", line 783 in exec_module File "", line 671 in _load_unlocked File "", line 975 in _find_and_load_unlocked File "", line 991 in _find_and_load File "/gnu/store/cjclqalblsxf8l6cn1l1r4qmyjab0di3-python-zarr-2.4.0/lib/python3.8/site-packages/zarr/__init__.py", li ne 3 in File "", line 219 in _call_with_frames_removed File "", line 783 in exec_module File "", line 671 in _load_unlocked File "", line 975 in _find_and_load_unlocked File "", line 991 in _find_and_load File "", line 219 in _call_with_frames_removed File "", line 961 in _find_and_load_unlocked File "", line 991 in _find_and_load File "/gnu/store/hynk61vdvgv3ha41lki2z1f4daqyn6b4-python-anndata-0.7.6/lib/python3.8/site-packages/anndata/compat/__i nit__.py", line 19 in File "", line 219 in _call_with_frames_removed File "", line 783 in exec_module File "", line 671 in _load_unlocked File "", line 975 in _find_and_load_unlocked File "", line 991 in _find_and_load File "/gnu/store/hynk61vdvgv3ha41lki2z1f4daqyn6b4-python-anndata-0.7.6/lib/python3.8/site-packages/anndata/_core/views.py", line 13 in File "", line 219 in _call_with_frames_removed File "", line 783 in exec_module File "", line 671 in _load_unlocked File "", line 975 in _find_and_load_unlocked File "", line 991 in _find_and_load File "/gnu/store/hynk61vdvgv3ha41lki2z1f4daqyn6b4-python-anndata-0.7.6/lib/python3.8/site-packages/anndata/_core/aligned_mapping.py", line 13 in File "", line 219 in _call_with_frames_removed File "", line 783 in exec_module File "", line 671 in _load_unlocked File "", line 975 in _find_and_load_unlocked File "", line 991 in _find_and_load File "/gnu/store/hynk61vdvgv3ha41lki2z1f4daqyn6b4-python-anndata-0.7.6/lib/python3.8/site-packages/anndata/_core/raw.py", line 11 in File "", line 219 in _call_with_frames_removed File "", line 783 in exec_module File "", line 671 in _load_unlocked File "", line 975 in _find_and_load_unlocked File "", line 991 in _find_and_load File "/gnu/store/hynk61vdvgv3ha41lki2z1f4daqyn6b4-python-anndata-0.7.6/lib/python3.8/site-packages/anndata/_core/anndata.py", line 26 in File "", line 219 in _call_with_frames_removed File "", line 783 in exec_module File "", line 671 in _load_unlocked File "", line 975 in _find_and_load_unlocked File "", line 991 in _find_and_load File "/gnu/store/hynk61vdvgv3ha41lki2z1f4daqyn6b4-python-anndata-0.7.6/lib/python3.8/site-packages/anndata/__init__.py", line 7 in File "", line 219 in _call_with_frames_removed File "", line 783 in exec_module File "", line 671 in _load_unlocked File "", line 975 in _find_and_load_unlocked File "", line 991 in _find_and_load File "/tmp/guix-build-python-scanpy-1.7.2.drv-0/scanpy-1.7.2/scanpy/_utils.py", line 18 in File "", line 219 in _call_with_frames_removed File "", line 783 in exec_module File "", line 671 in _load_unlocked File "", line 975 in _find_and_load_unlocked File "", line 991 in _find_and_load File "/tmp/guix-build-python-scanpy-1.7.2.drv-0/scanpy-1.7.2/scanpy/__init__.py", line 5 in File "", line 219 in _call_with_frames_removed File "", line 783 in exec_module File "", line 671 in _load_unlocked File "", line 975 in _find_and_load_unlocked File "", line 991 in _find_and_load File "/tmp/guix-build-python-scanpy-1.7.2.drv-0/scanpy-1.7.2/scanpy/tests/conftest.py", line 11 in File "/gnu/store/436410968f8mpdlsn1pw456mpgwmbh4m-python-pytest-5.3.5/lib/python3.8/site-packages/_pytest/assertion/rewrite.py", line 143 in exec_module File "", line 671 in _load_unlocked File "", line 975 in _find_and_load_unlocked File "", line 991 in _find_and_load File "/gnu/store/avj1ma4bvfjnw86pd9ys64899b627f0x-python-py-1.8.1/lib/python3.8/site-packages/py/_path/local.py", line 701 in pyimport File "/gnu/store/436410968f8mpdlsn1pw456mpgwmbh4m-python-pytest-5.3.5/lib/python3.8/site-packages/_pytest/config/__init__.py", line 465 in _importconftest File "/gnu/store/436410968f8mpdlsn1pw456mpgwmbh4m-python-pytest-5.3.5/lib/python3.8/site-packages/_pytest/config/__init__.py", line 437 in _getconftestmodules File "/gnu/store/436410968f8mpdlsn1pw456mpgwmbh4m-python-pytest-5.3.5/lib/python3.8/site-packages/_pytest/main.py", line 445 in gethookproxy File "/gnu/store/436410968f8mpdlsn1pw456mpgwmbh4m-python-pytest-5.3.5/lib/python3.8/site-packages/_pytest/main.py", line 626 in _recurse File "/gnu/store/avj1ma4bvfjnw86pd9ys64899b627f0x-python-py-1.8.1/lib/python3.8/site-packages/py/_path/common.py", line 425 in File "/gnu/store/avj1ma4bvfjnw86pd9ys64899b627f0x-python-py-1.8.1/lib/python3.8/site-packages/py/_path/common.py", line 424 in gen File "/gnu/store/avj1ma4bvfjnw86pd9ys64899b627f0x-python-py-1.8.1/lib/python3.8/site-packages/py/_path/common.py", line 435 in gen File "/gnu/store/avj1ma4bvfjnw86pd9ys64899b627f0x-python-py-1.8.1/lib/python3.8/site-packages/py/_path/common.py", line 383 in visit File "/gnu/store/436410968f8mpdlsn1pw456mpgwmbh4m-python-pytest-5.3.5/lib/python3.8/site-packages/_pytest/main.py", line 545 in _collect File "/gnu/store/436410968f8mpdlsn1pw456mpgwmbh4m-python-pytest-5.3.5/lib/python3.8/site-packages/_pytest/main.py", line 504 in collect File "/gnu/store/436410968f8mpdlsn1pw456mpgwmbh4m-python-pytest-5.3.5/lib/python3.8/site-packages/_pytest/runner.py", line 257 in File "/gnu/store/436410968f8mpdlsn1pw456mpgwmbh4m-python-pytest-5.3.5/lib/python3.8/site-packages/_pytest/runner.py", line 237 in from_call File "/gnu/store/436410968f8mpdlsn1pw456mpgwmbh4m-python-pytest-5.3.5/lib/python3.8/site-packages/_pytest/runner.py", line 257 in pytest_make_collect_report File "/gnu/store/nqi6xqx8h2fxldi3xbigkc24wfzzsy5j-python-pluggy-0.13.1/lib/python3.8/site-packages/pluggy/callers.py", line 187 in _multicall File "/gnu/store/nqi6xqx8h2fxldi3xbigkc24wfzzsy5j-python-pluggy-0.13.1/lib/python3.8/site-packages/pluggy/manager.py", line 84 in File "/gnu/store/nqi6xqx8h2fxldi3xbigkc24wfzzsy5j-python-pluggy-0.13.1/lib/python3.8/site-packages/pluggy/manager.py", line 93 in _hookexec File "/gnu/store/nqi6xqx8h2fxldi3xbigkc24wfzzsy5j-python-pluggy-0.13.1/lib/python3.8/site-packages/pluggy/hooks.py", line 286 in __call__ File "/gnu/store/436410968f8mpdlsn1pw456mpgwmbh4m-python-pytest-5.3.5/lib/python3.8/site-packages/_pytest/runner.py", line 379 in collect_one_node ... command "pytest" failed with signal 4 builder for `/gnu/store/xdqc4a2xhkiknasj8rk36gl3gr5iswr8-python-scanpy-1.7.2.drv' failed with exit code 1 build of /gnu/store/xdqc4a2xhkiknasj8rk36gl3gr5iswr8-python-scanpy-1.7.2.drv failed --8<---------------cut here---------------end--------------->8--- It would seem that one of these dependencies has code using x86_64 ISA extensions that this particular CPU doesn’t support. Thoughts? Ludo’.