OpenCL memory allocation fails at least in test

[drahnr]

https://ci.spearow.io/teams/spearow/pipelines/juice/jobs/test-coaster/builds/69

# RUST_BACKTRACE=1 cargo t --verbose -- --nocapture backend_spec::opencl
       Fresh rustc-serialize v0.3.24
       Fresh num-traits v0.1.40
       Fresh libc v0.2.31
       Fresh lazy_static v0.1.16
       Fresh bitflags v0.3.3
       Fresh utf8-ranges v1.0.0
       Fresh byteorder v0.4.2
       Fresh regex-syntax v0.4.1
       Fresh lazy_static v0.2.8
       Fresh void v1.0.2
       Fresh enum_primitive v0.1.1
       Fresh num-integer v0.1.35
       Fresh num-complex v0.1.40
       Fresh rand v0.3.16
       Fresh memchr v1.0.1
       Fresh unreachable v1.0.0
       Fresh num-iter v0.1.34
       Fresh num-bigint v0.1.40
       Fresh aho-corasick v0.6.3
       Fresh thread_local v0.3.4
       Fresh num-rational v0.1.39
       Fresh regex v0.2.2
       Fresh num v0.1.40
       Fresh coaster v0.1.0 (file:///tmp/build/74b91f0c/coaster)
    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `/tmp/build/74b91f0c/coaster/target/debug/deps/coaster-4378b988abc30558 --nocapture 'backend_spec::opencl'`

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

     Running `/tmp/build/74b91f0c/coaster/target/debug/deps/backend_specs-d18603f981e40185 --nocapture 'backend_spec::opencl'`

running 2 tests
error: process didn't exit successfully: `/tmp/build/74b91f0c/coaster/target/debug/deps/backend_specs-d18603f981e40185 --nocapture backend_spec::opencl` (signal: 11, SIGSEGV: invalid memory reference)

[drahnr]

Backend::<OpenCL>::default() fails and thus it_can_create_default_backend fails. it_can_manually_create_default_backend works.

[drahnr]

It works because it is missing the assert! statement.

[drahnr]

Err(Framework(OpenCL(InvalidDevice("devices contains an invalid device.")))) is the core issue, OpenCL return code -33.

[drahnr]

It seems that at least intel beignet opencl implementation can not handle multiple devices from different platforms all at once. using just the first works fine. Removing pocl for possible interference.

[drahnr]

There is also amdgpu-pro opencl missing in the containers...

Result:

• without pocl things work again, but...
• there is only one cl_platform left, which
• requires AMDGPU-PRO to install the OpenCL part on root and in the container to verify if this is a red hering or not

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clContextCreate does not state any constraints regarding the list of devices allowed to be passed.

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Actually POCL is the CPU implementation, so that should be fine.