Is Optix 7.4 in the R470 drivers?

Hello,

There is a discrepancy with the OptiX version numbers between the release notes and actual driver files.

  • The release notes state: “OptiX 7.4 requires an Nvidia display driver numbered 495 or higher”
  • Drivers 471.11 through 473.04 all include an nvoptix.dll that is versioned 7.4.0.
  • Driver 466.77 has version nvoptix.dll version 7.3.0.

Why was the version changed from 7.3 to 7.4 with the R470 branch? I would have expected this to be a change made in R495, but I can’t imagine this is a fluke on nvidia’s part.

This leads me to ask: is there OptiX 7.4 functionality in the R470 drivers? The 7.4.0 version tag and the +30MB increase from 7.3.0 in nvoptix.dll seems to indicate that something substantial was indeed added in R470, but calling optixQueryFunctionTable with ABI 55 on the R470 drivers gives error 7801, which is consistent with the release notes. Perhaps there is some non-public OPTIX_ABI_VERSION between R470’s 47 and R495’s 55 that has a subset of the officially documented 7.4 API?

I’d like to know more about this oddity and whether or not I can use some/all/early OptiX 7.4 features on R470 drivers. If you have details, please share. Thanks much in advance.

Hi @definitive-precept, welcome.

Very sharp eyes! This appears to be a merge accident and wasn’t supposed to happen. R470 is still receiving support updates, and got a newer version of the optix dll that it wasn’t supposed to.

So, while OptiX 7.4 might work temporarily in the R470 branch, this wasn’t intended and is going to be corrected in the next release. The R470 branch should be locked at OptiX version 7.3 (indeed, this is part of the point of having versioned branch numbers). Sorry if we got your hopes up, but thank you for calling our attention to this!


David.

OptiX 7.4 might work temporarily in the R470 branch

Can you elaborate on this? Are there any confirmed cases of applications targeting OptiX 7.4 running successfully on R470? optixQueryFunctionTable on R470 fails with any ABI version >= 48. I’d really like to know how to access the 7.4 interface if it genuinely does exist on R470.

This appears to be a merge accident and wasn’t supposed to happen … and is going to be corrected in the next release

Bob Ross tells us to welcome the happy accidents and not to revert them :) I’d like to think that whoever caused this “merge accident” agrees, since it has survived this long without discovery (and thus without major issues!). Please do reconsider eliminating it from R470.

Can you elaborate on this? Are there any confirmed cases of applications targeting OptiX 7.4 running successfully on R470?

No, not to my knowledge, and we absolutely advise against trying to use OptiX 7.4 with R470. All I meant to say is that I don’t even know if the version numbers you’re seeing include all the functionality of OptiX 7.4 or not. The DLL might be accidentally functional, or it might have been only strings that were bumped accidentally, I don’t know the extent of the problem, only that it’s going to be rectified in the next release.

I’d really like to know how to access the 7.4 interface

Regardless of the driver version, you just need to download the OptiX 7.4 SDK and build against it. It might happen to work with the R470 driver you have, or it might not. If it happens to work, one option is to keep this driver and not update again until you can move to a R495 driver. I recommend against this, but we can’t change the driver you already have, we can only release an update to R470.

Please do reconsider eliminating it from R470.

This unfortunately isn’t even up to the OptiX team. Including the new DLL is breaking promises we’ve already made to customers not to destabilize a branch with new unexpected and untested feature combinations. OptiX 7.4 has not gone through QA on the R470 branch, and may crash. Since this isn’t the last update to R470, we don’t have a choice but to revert the change and correct the situation so that it lines up with the documented plan.


David.

Thanks for the quick reply. I understand the enterprise obligations, unfortunate as they may be for a hobbyist like myself.

Regardless of the driver version, you just need to download the OptiX 7.4 SDK and build against it

This is what I have been testing with, without any luck. I also have an application (not mine) that was built with OptiX 7.4 that I am trying to get to function correctly on a R470 driver. If 7.4 does exist in R470, it certainly isn’t exposed to the 7.4 SDK’s headers.

Thanks again for all the great info and fast responses!

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