CODEWITHSUNDEEP
openclversionplatform
huseyin tugrul buyukisik
huseyin tugrul buyukisik

Reputation: 11910

How do OpenCL platforms are listed for OpenCL-2.0 devices?

I need to implement a truly working platform version filter targeted to version 1.2 for my open-source project: https://github.com/tugrul512bit/Cekirdekler

I don't have 150$ to buy an OpenCL2.0 capable graphics card for now so I'm working on a pure-1.2 version system and not sure about other (new)systems.

Question: How does a list of platforms looks like when there are only opencl 2.0 capable gpus and both 1.2(max) and 2.0(max) capable gpus exist in same system?

Lets assume I'm using this

clGetPlatformIDs()

to get a list. Should I suppose it gives only single version platforms per device or,

For example, a GTX-Titan XP(opencl 2.0 capable?) can list two platforms:

separately for same device? Or it just gives 2.0 version?

What about a GTX-TitanXP and a GT-640?

or

which one happens?

Can this change with drivers?

What about OpenCL version 2.3 GPUs? Do they seem as 2.0 in OpenCL API or correctly give 3 as minor version?

If anyone could share his/hers experience, I appreciate.

For now, project can take 1.2 or 2.0 versions (Intel drivers I installed have an experimental version 2.1 with bugs so I filter-out with minor version checking, I'm not sure if Nvidia or Amd can do similar or opposite things in OpenCL-2.x capable cards). I can also filter for platform names "experimental"/"beta" to elliminate such platforms but I'm not sure if there are multiple versions for same GPUs.

I assume 2.0 devices have backwards compatilibity for 1.2 but do I need anything extra to enable 1.2 spec? For now I'm not doing anything extra for 1.2 devices. Maybe 2.0 needs some?

Upvotes: 0

Views: 1506

Answers (1)

Dithermaster
Dithermaster

Reputation: 6333

Each platform returns its own version number independently of the others. You can have a mix, for example a GPU at 1.2 and a CPU driver at 2.0.

If you make only OpenCL 1.2 API calls you can use either. If you make OpenCL 2.0 API calls you can only use 2.0 or higher platforms.

Likewise, devices within a platform can return their own version numbers, although I don't think they can be larger than their parent platform number. An example of this is an older GPU, which might only be OpenCL 1.1 even though the platform is 1.2.

Separate from this is the version of OpenCL kernel language each device supports. For backwards compatibility if you don't pass compile options you are getting OpenCL C 1.x. If you are on a 2.x device you can pass an option string when compiling your kernel to get new language features.

Upvotes: 2

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