[ I'm fairly new to OpenCL and ROCm, so I may be wrong - please take
everything with a grain of salt. ]

rocm-opencl-icd currently Conflicts with mesa-opencl-icd and
pocl-opencl-icd.

This, for example, prevents one from utilizing both ROCm (for GPU) and
PoCL (for CPU) at the same time -- in different applications or even in
the same one (hashcat, for example, supports this).

My understanding is that the *-opencl-icd packages are intended to be
co-installable, and the OpenCL stack is modular enough to support
multiple platforms and devices, co-existing with each other.

I tested this by force-installing rocm + pocl, and indeed it installed
fine (no file conflicts) and clinfo and hashcat report both of them now.
I can select specific devices with hashcat's --opencl-devices option.

The package's changelog suggests this Conflicts (Breaks originally) was
added a long time ago (5.7.1-4) because of an "LLVM load error", but I
could not reproduce this - at least not with the combination of rocm +
pocl (I did not test with mesa).

Regards,
Faidon