Re: [RFC PATCH] misc: fgds: enable GPU-NVMe direct I/O via POSIX and io_uring

[Christian König]

On 9/9/26 15:35, Greg Kroah-Hartman wrote:
> On Wed, Sep 09, 2026 at 06:42:03PM +0800, Li Wang wrote:
>> Hi Greg,
>>   Thanks for the review!
>>
>>>
>>> That's not really needed in a changelog text, it could be in the 0/X
>>> patch :)
>>>
>> Sorry for the clutter. I will move most of them into the 0/X patch in v2.
>>
>>> Anyway, you didn't cc: the io_uring list, why?
>>>
>> `scripts/get_maintainer.pl` didn't output the io_uring mailing list, likely 
>> because this patch doesn't directly touch the io_uring codebase itself. It only 
>> enables remapping GPU memory buffers to CPU virtual addresses, which can then be 
>> consumed via standard io_uring APIs.
>>
>> I've added io-uring@xxxxxxxxxxxxxxx to CC for this reply and will keep it in v2.
> 
> Great, as you are using that as the api, there might be some parts that
> will need to be reviewed by them.
> 
>>> Nor why "fgds" is the name, that's going to be hard to remember, does it
>>> stand for something?
>>>
>> "FGDS" stands for Fast GPUDirect Storage. GPUDirect Storage (GDS) is NVIDIA's 
>> technology enabling direct I/O between GPU memory and files on NVMe, 
>> widely used in LLM workloads to bypass CPU overhead.
> 
> That's nvidia's specific solution, but this works on other devices,
> right?  Or just for that one platform?

That was nvidia's specific and very hacky out of tree solution which as far as I know is pretty much abandoned everywhere.

AMD came up with something similar, but all those approaches are so fundamentally broken that we didn't even considered upstreaming it.
> And you are using this as a "bypass" for the normal accel subsystem,
> shouldn't this be part of that subsystem instead of a custom user/kernel
> api like you are creating here?

As far as I know there is a patch set under review and even already partially merged which enables exactly that functionality as general feature for DMA-buf which is vendor independent and should at least in theory work with all drivers.

I'm really surprised that somebody is still working on the vendor specific stuff.

Regards,
Christian.

> 
> thanks,
> 
> greg k-h