Re: [PATCH v4 0/2] Add p2p via dmabuf to habanalabs

Jason Gunthorpe
2021-07-06T14:43:34Z

On Tue, Jul 06, 2021 at 12:36:51PM +0200, Daniel Vetter wrote:

> If that means AI companies don't want to open our their hw specs
> enough to allow that, so be it - all you get in that case is
> offloading the kernel side of the stack for convenience, with zero
> long term prospects to ever make this into a cross vendor subsystem
> stack that does something useful.

I don't think this is true at all - nouveau is probably the best
example.

nouveau reverse engineered a userspace stack for one of these devices.

How much further ahead would they have been by now if they had a
vendor supported, fully featured, open kernel driver to build the
userspace upon?

> open up your hw enough for that, I really don't see the point in
> merging such a driver, it'll be an unmaintainable stack by anyone else
> who's not having access to those NDA covered specs and patents and
> everything.

My perspective from RDMA is that the drivers are black boxes. I can
hack around the interface layers but there is a lot of wild stuff in
there that can't be understood without access to the HW documentation.

I think only HW that has open specs, like say NVMe, can really be
properly community oriented. Otherwise we have to work in a community
partnership with the vendor.

Jason