[Pkg-opencl-devel] pocl ITP, and opencl-icd selection

[Vincent Danjean]

  Hi,

On 05/02/2014 00:15, Rebecca N. Palmer wrote:
> 1) The pocl proposed package (ITP #676504,
> https://alioth.debian.org/anonscm/git/collab-maint/pocl.git)
> has not been touched for approximately a year; did it hit a
> technical problem, or have you just not had time?

  Initially, it was technical problems (mainly (sub)architecture
detection at compilation time). But, to my knowledge, this has
been correctly addressed and fixed upstream.
  Then, it is only lack of time.

  The packaging is done in the git repo in the colab-maint project
on alioth. Any one-time help (importing and testing the pre 0.9
releases, ...) or even co-maintainer on the long term is really
welcome.

> 2) Do you have a plan for how to ensure the correct ICD for the
> hardware is installed?

  No, and I do not see any way to do this. There is no hardware
information for the dependency system (but the "main" architecture
such as i386/amd64/armel/...) If we got a free implementation
that "works" (not necessarily optimized) nearly everywhere (pocl ?),
then we can imagine to put it as the first alternative dependency.

  Your two proposal are also very interesting. The difference
with xorg is that xorg choose the "good" driver at runtime if all
are installed. This is not the case with OpenCL. For example,
if beignet is installed on a machine where it does not work,
it can be selected as the default implementation by libOpenCL.so.1
(but if its initializer does not report any plateform on non-supported
environment, I did not checked).

  I think the first step is to package pocl. Then, we can try
to improve dependencies so that OpenCL applications work on
all machine by default (sometime, OpenCL applications require
specifically a GPU device. Should we fallback on CPU device if
none are available ?). Perhaps, the ICD loader of ocl-icl can be
improved to add specific runtime detection in order to choose
the best default implementation when several are available
(perhaps with the help of ICDs themselves).

  Regards,
    Vincent

PS: I will be without internet access for 1 week.

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