https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99555
--- Comment #17 from Tom de Vries <vries at gcc dot gnu.org> --- (In reply to Thomas Schwinge from comment #14) > > That's with a Nvidia Tesla K20c GPU, Driver Version: 346.46. > > As that version is "a bit old", I shall first update this, before we spend > > any further time on analyzing this. > > Cross-checking on another system with Nvidia Tesla K20c GPU but more recent > Driver Version I'm not seeing such an issue. > > On the "old" system, gradually upgrading Driver Version: 346.46 to 352.99, > 361.93.02, 375.88 (always the latest (?) version of the respective series), > these all did not resolve the problem. > > Only starting with 384.59 (that is, early version of the 384.X series), that > then did resolve the issue. That's still using the GCC/nvptx '-mptx=3.1' > multilib. > > (We couldn't with earlier series, but given this is 384.X, we may now also > cross-check with the default multilib, and that also was fine.) > > Now, I don't know if at all we would like to spend any more effort on this > issue, given that it only appears with rather old pre-384.X versions -- but > on the other hand, the GCC/nvptx '-mptx=3.1' multilib is meant to keep these > supported? (... which is why I'm running such testing; and certainly the > timeouts are annoying there.) > > It might be another issue with pre-384.X versions of the Nvidia PTX JIT, or > is there the slight possibility that GCC is generating/libgomp contains some > "weird" code that post-384.X version happen to "fix up" -- probably the > former rather than the latter? (Or, the chance of GPU hardware/firmware or > some other system weirdness -- unlikely, otherwise behaves totally fine?) > > I don't know where to find complete Nvidia Driver/JIT release notes, where > the 375.X -> 384.X notes might provide an idea of what got fixed, and we > might then add another 'WORKAROUND_PTXJIT_BUG' for that -- maybe simple, > maybe not. > > Any thoughts, Tom? I care about old cards, not about old drivers. The oldest card we support is an sm_30, and last driver series that supports that one is 470.x (and AFAIU, is therefore supported by nvidia for that arch). There's the legacy series, 390.x, which is the last to support fermi, but we don't support any fermi cards or earlier. I did do some testing with this one for later cards, but reported issues are acknowledged but not fixed by nvidia, so ... this is already out of scope for me. So yeah, IWBN to come up with workarounds for various older drivers, but I'm not investing time in that. Is there a problem for you to move to 470.x or later (515.x) ? Is there a card for which that causes problems ?
