Re: [MAINTAINER SUMMIT] User-space requirements for accelerator drivers

From: Dave Airlie <airlied@gmail.com>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Greg KH <greg@kroah.com>, Leon Romanovsky <leon@kernel.org>,
	 Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	 Josh Triplett <josh@joshtriplett.org>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	 Jonathan Corbet <corbet@lwn.net>,
	ksummit@lists.linux.dev
Subject: Re: [MAINTAINER SUMMIT] User-space requirements for accelerator drivers
Date: Mon, 13 Sep 2021 07:12:49 +1000	[thread overview]
Message-ID: <CAPM=9txdCs-pXfw1Q=o_tMcmPafHcwV6_K5Sh=Vnj6d=G-tm_A@mail.gmail.com> (raw)
In-Reply-To: <CAKMK7uHQw8=GKpayxzOJUs4BnwoVDS08Y9bynp6=VH+eW35Pgw@mail.gmail.com>

On Mon, 13 Sept 2021 at 06:49, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
>
> On Sun, Sep 12, 2021 at 10:41 PM Dave Airlie <airlied@gmail.com> wrote:
> > > So will the IB patches usage be re-reviewed?
> >
> > https://lore.kernel.org/linux-rdma/MW3PR11MB4555CCCDD42F1ADEC61F7ACAE5AB0@MW3PR11MB4555.namprd11.prod.outlook.com/
> >
> > FYI it's a thread where GPU devs reviewing IB dma-buf patches, what's
> > next cat and dogs living together?
>
> And as you can see, the review has been long and involved a ton of
> different dri-devel (and rdma ofc too) folks.
>
> It's like there's an entire community of experts at hands who could
> help out in reviewing these things, if only we'd not have a maintainer
> who happily bypasses all that and invites all the dumpster fires into
> drivers/misc. And then complains that no one helps with reviewing ...
> -Daniel

Daniel makes a good point here about "communities of experts".

We need to foster those cross-vendor expert communities to sustain
Linux going forward.

For userspace components as well these communities of experts need to
exist for each domain, and we need to encourage upstream first
processes across the board for these split kernel/userspace stacks.

The habanalabs compiler backend is an LLVM fork, I'd like to see the
effort to upstream that LLVM backend into LLVM proper. When this sort
of thing happens it gets on the radar of the LLVM compiler experts,
instead of it just being the habanalabs experts. I've met so many
internal company experts who remain unchallenged internally but buckle
when introduced to true communities of expertise. If we want to keep
this thing growing and maintainable we need to tap into those existing
expertise groups. This is why it's important we foster userspace
groups. If you hear the myth that only our company understands our hw
enough to write code for it, it's been proven bullshit numerous times.
It's an excuse for retaining control.

Also if there was a shared runtime library repo with cross vendor
review, I'm betting they'd all learn a lot about how a userspace
should work and be maintained rather than assuming they knew it all
themselves.

Be more like spiderman, great maintainership + great responsibility.

Dave.