Subject: Re: [PATCH V2 3/5] vDPA: introduce vDPA bus

From: Jason Gunthorpe <[email-masked]>
Date: Tue, 18 Feb 2020 13:56:12 +0000

On Mon, Feb 17, 2020 at 02:08:03PM +0800, Jason Wang wrote:

> I thought you were copied in the patch [1], maybe we can move vhost related
> discussion there to avoid confusion.
>
> [1] https://lwn.net/Articles/811210/

Wow, that is .. confusing.

So this is supposed to duplicate the uAPI of vhost-user? But it is
open coded and duplicated because .. vdpa?

> So it's cheaper and simpler to introduce a new bus instead of refactoring a
> well known bus and API where brunches of drivers and devices had been
> implemented for years.

If you reason for this approach is to ease the implementation then you
should talk about it in the cover letters/etc

Maybe it is reasonable to do this because the rework is too great, I
don't know, but to me this whole thing looks rather messy. 

Remember this stuff is all uAPI as it shows up in sysfs, so you can
easilly get stuck with it forever.

Jason