Hi! On Fri, 8 Nov 2013 16:40:00 +0100, Jakub Jelinek <ja...@redhat.com> wrote: > On Fri, Nov 08, 2013 at 04:29:03PM +0100, Thomas Schwinge wrote: > > > > On the gomp-4_0-branch, when using the ID 257 device (host fallback but > > with non-shared memory), I see the libgomp.c/target-1.c test fail in > > fn2's GOMP_target_update call: > > > > libgomp: Trying to update [0x601a80..0x601a84) object that is not mapped > > > > Is this a known issue? (I have not yet started debugging that, and > > figured someone more familiar with the code may perhaps easily be able to > > tell what's going wrong.) > > That is expected, device 257 is just a temporary testing hack, which doesn't > support > variables with "omp declare target" attribute. > So, you can only use it for testcases that don't have any #pragma omp > declare target variables, or if they do, they only access them in #pragma > omp declare target functions, but never try to use them or anything related > to them in map/to/from clauses. > The plan is that using the two proposed tables (host table of host_addr, size > pairs and corresponding target table of target_addr) during initialization > of offloading for a particular shared library resp. binary libgomp will > register all those ranges in the mapping table.
> [...], once we have at least one supported offloading target, > hopefully we'll nuke device 257. Hmm, in contrast, I'd advocate to preserve that device, under a proper ID, for two (similar) reasons: even if it's the same architecture, we'll still want a generic non-shared-memory "offloading target" for GCC testsuite usage. We can't assume that any of the "real hardware" acceleration devices to be available, but will still want to test the non-shared-memory stuff. And likewise, GCC users can use this for testing their code for shared-memory host (fallback) execution vs. non-shared-memory execution. So basically, just like a user can decide to use OpenMP/libgomp, but tie the runtime down to just one thread; but that's still different from host fallback execution. Makes sense? Grüße, Thomas
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