Failed to install flash-attn on Mac OSX #1

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1. zhongl

   changed the title [-]Failed to install flash-attn[/-] [+]Failed to install flash-attn on Mac OSX[/+] on Aug 28, 2025
2. zhongl commented on Aug 28, 2025

   

   zhongl

   on Aug 28, 2025

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   After install torch by hand, new error happens:

   Pip subprocess error:
     error: subprocess-exited-with-error
   
     × python setup.py egg_info did not run successfully.
     │ exit code: 1
     ╰─> [21 lines of output]
         /private/var/folders/dq/dp0bbpdj7tg9sm46bzynwv9m0000gn/T/pip-install-avkc9l69/flash-attn_ccb8da609c1049a6b82129648595c66f/setup.py:106: UserWarning: flash_attn was requested, but nvcc was not found.  Are you sure your environment has nvcc available?  If you're installing within a container from https://hub.docker.com/r/pytorch/pytorch, only images whose names contain 'devel' will provide nvcc.
           warnings.warn(
         Traceback (most recent call last):
           File "<string>", line 2, in <module>
           File "<pip-setuptools-caller>", line 35, in <module>
           File "/private/var/folders/dq/dp0bbpdj7tg9sm46bzynwv9m0000gn/T/pip-install-avkc9l69/flash-attn_ccb8da609c1049a6b82129648595c66f/setup.py", line 227, in <module>
             CUDAExtension(
           File "/opt/homebrew/Caskroom/miniforge/base/envs/.conda/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 1279, in CUDAExtension
             library_dirs += library_paths(device_type="cuda")
                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
           File "/opt/homebrew/Caskroom/miniforge/base/envs/.conda/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 1508, in library_paths
             if (not os.path.exists(_join_cuda_home(lib_dir)) and
                                    ^^^^^^^^^^^^^^^^^^^^^^^^
           File "/opt/homebrew/Caskroom/miniforge/base/envs/.conda/lib/python3.12/site-packages/torch/utils/cpp_extension.py", line 2907, in _join_cuda_home
             raise OSError('CUDA_HOME environment variable is not set. '
         OSError: CUDA_HOME environment variable is not set. Please set it to your CUDA install root.
   
   
         torch.__version__  = 2.7.1
   
   
         [end of output]
   
     note: This error originates from a subprocess, and is likely not a problem with pip.
   error: metadata-generation-failed
   
   × Encountered error while generating package metadata.
   ╰─> See above for output.
   
   note: This is an issue with the package mentioned above, not pip.
   hint: See above for details.