ocl-icd 2.3.1 (new formula)

[cho-m]

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Split off from #103141

See other PR for why this we need to use this instead of opencl-icd-loader.

Also, this is the option most major Linux distros have picked (https://repology.org/project/ocl-icd/versions) like Debian/Ubuntu, Fedora, Arch, Gentoo, ...

[danielnachun]

I finally had a chance to test all 9 of the OpenCL formulae using this + pocl and opencl-headers. All the formulae except cf4ocl built without much fuss, and the problem with cf4ocl seems unrelated to how we are packaging OpenCL.

During the testing things did not work quite as well. clinfo, clfft and hashcat all threw some sort of error because they couldn't find an OpenCL device. I'm not yet sure if this because they don't know to search HOMEBREW_PREFIX/etc/OpenCL/vendors or because of some other issue with pocl. I'll be looking into this more but @cho-m let me know if you have any other thoughts.

[cho-m]

During the testing things did not work quite as well. clinfo, clfft and hashcat all threw some sort of error because they couldn't find an OpenCL device. I'm not yet sure if this because they don't know to search HOMEBREW_PREFIX/etc/OpenCL/vendors or because of some other issue with pocl. I'll be looking into this more but @cho-m let me know if you have any other thoughts.

Not sure. I was able to use clinfo and hashcat in Linux Docker container with just having dependencies.

It was even possible to build clinfo without adding dependencies to formula and get it to run (due to HOMEBREW_PREFIX/lib in RPATH). In this example, you can see it fail once ocl-icd is unlinked:

$ clinfo
Number of platforms                               1
  Platform Name                                   Portable Computing Language
  Platform Vendor                                 The pocl project
  Platform Version                                OpenCL 3.0 PoCL 3.0-rc2  Linux, Release, RELOC, LLVM 14.0.6, SLEEF, DISTRO, POCL_DEBUG
...
ICD loader properties
  ICD loader Name                                 OpenCL ICD Loader
  ICD loader Vendor                               OCL Icd free software
  ICD loader Version                              2.3.1
  ICD loader Profile                              OpenCL 3.0

$ brew unlink ocl-icd
Unlinking /home/linuxbrew/.linuxbrew/Cellar/ocl-icd/2.3.1... 10 symlinks removed.

$ clinfo
clinfo: error while loading shared libraries: libOpenCL.so.1: cannot open shared object file: No such file or directory

[danielnachun]

Not sure. I was able to use clinfo and hashcat in Linux Docker container with just having dependencies.

It was even possible to build clinfo without adding dependencies to formula and get it to run (due to HOMEBREW_PREFIX/lib in RPATH). In this example, you can see it fail once ocl-icd is unlinked:

$ clinfo
Number of platforms                               1
  Platform Name                                   Portable Computing Language
  Platform Vendor                                 The pocl project
  Platform Version                                OpenCL 3.0 PoCL 3.0-rc2  Linux, Release, RELOC, LLVM 14.0.6, SLEEF, DISTRO, POCL_DEBUG
...
ICD loader properties
  ICD loader Name                                 OpenCL ICD Loader
  ICD loader Vendor                               OCL Icd free software
  ICD loader Version                              2.3.1
  ICD loader Profile                              OpenCL 3.0

$ brew unlink ocl-icd
Unlinking /home/linuxbrew/.linuxbrew/Cellar/ocl-icd/2.3.1... 10 symlinks removed.

$ clinfo
clinfo: error while loading shared libraries: libOpenCL.so.1: cannot open shared object file: No such file or directory

Okay that's very helpful to know. I'll double check this and see if I can get clinfo, hashcat and clfft to work. If there's no issues with them I think we will be very close to merging this!

[danielnachun]

I was able to get hashcat and clinfo to work after upgrading the pocl formula to 3.0. The test binary for clfft still segfaults, possibly because it still isn't detecting an OpenCL device. However I think there is enough evidence that this is working as expected that I'm ready to approve this once we resolve the etc issue.

[danielnachun]

Let's rephrase this to:

No OpenCL implementation is pre-installed, so all dependents will require either
installing a compatible formula or creating an ".icd" file mapping to an externally
installed implementation. Any ".icd" files copied or symlinked into 
`#{etc}/OpenCL/vendors` will automatically be detected by `ocl-icd`. A portable
OpenCL implementation is available via the `pocl` formula.

Please fix anything that may be incorrect there!

[danielnachun]

I think this is ready to publish now.

[BrewTestBot]

@danielnachun has triggered a merge.