From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Jonathan Corbet <corbet@lwn.net>, ksummit@lists.linux.dev
Subject: Re: [MAINTAINER SUMMIT] User-space requirements for accelerator drivers
Date: Fri, 10 Sep 2021 15:35:06 -0700 [thread overview]
Message-ID: <05c1591b0e3744233e78ae35ba66d2721ee6af5e.camel@HansenPartnership.com> (raw)
In-Reply-To: <YTvVKrfyMc7fKsZx@piout.net>
On Fri, 2021-09-10 at 23:59 +0200, Alexandre Belloni wrote:
> On 10/09/2021 14:51:43-0700, James Bottomley wrote:
> > On Fri, 2021-09-10 at 15:00 -0600, Jonathan Corbet wrote:
> > > - Are there internal kernel interfaces, such as DMA-BUF or
> > > P2PDMA, that are only available to drivers with a free user-space
> > > implementation? Do we need an EXPORT_SYMBOL_USERSPACE_GPL()?
> >
> > I don't think reasonably we can do this. The kernel GPLv2 licence
> > includes this system exception:
> >
> > NOTE! This copyright does *not* cover user programs that use
> > kernel services by normal system calls - this is merely
> > considered
> > normal use of the kernel, and does *not* fall under the heading
> > of
> > "derived work". Also note that the GPL below is copyrighted by
> > the
> > Free Software Foundation, but the instance of code that it
> > refers to
> > (the Linux kernel) is copyrighted by me and others who actually
> > wrote it.
> >
> > Also note that the only valid version of the GPL as far as the
> > kernel is concerned is _this_ particular version of the license
> > (ie
> > v2, not v2.2 or v3.x or whatever), unless explicitly otherwise
> > stated.
> >
> > This means currently that once an API is exposed to user space,
> > we've given up control of the type of programme (proprietary or
> > open source) that may use it.
> >
> > It might be possible legally to try and take back that control by
> > modifying the system exception (what is a "normal" system call),
> > but I personally think that would be unwise and create a raft of
> > other problems for other proprietary user space code running on
> > Linux, which I really think we don't want to do.
> >
> > I think our only recourse for user space accelerators is not to
> > export the interface if we think it would only be used for evil
> > purposes.
> >
>
> I think the question is not whether we want to forbid proprietary
> user space using an API but whether we want to merge said API so the
> license on the kernel doesn't matter much.
I thought that *was* the statement I made in the last paragraph: we can
choose whether or not to merge the enabling API into the kernel.
However, if we merge it we can't choose whether a proprietary user
space takes advantage of the API. My original reply was to the notion
of EXPORT_USERSPACE_GPL, which I think we have no legal basis for
enforcing without modifying the system exception.
James
next prev parent reply other threads:[~2021-09-10 22:35 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-10 21:00 [MAINTAINER SUMMIT] User-space requirements for accelerator drivers Jonathan Corbet
2021-09-10 21:32 ` Josh Triplett
2021-09-13 13:50 ` Christian Brauner
2021-09-13 13:57 ` Daniel Vetter
2021-09-14 2:07 ` Laurent Pinchart
2021-09-14 14:40 ` Jani Nikula
2021-09-14 14:45 ` Geert Uytterhoeven
2021-09-14 14:59 ` Jani Nikula
2021-09-14 15:10 ` Geert Uytterhoeven
2021-09-10 21:51 ` James Bottomley
2021-09-10 21:59 ` Alexandre Belloni
2021-09-10 22:35 ` James Bottomley [this message]
2021-09-11 14:51 ` Jonathan Corbet
2021-09-11 15:24 ` James Bottomley
2021-09-11 21:52 ` Laurent Pinchart
2021-09-14 13:22 ` Johannes Berg
2021-09-11 0:08 ` Laurent Pinchart
2021-09-10 22:52 ` Mauro Carvalho Chehab
2021-09-10 23:45 ` Josh Triplett
2021-09-10 23:48 ` Dave Hansen
2021-09-11 0:13 ` Laurent Pinchart
2021-09-10 23:55 ` Thomas Gleixner
2021-09-11 0:20 ` Laurent Pinchart
2021-09-11 14:20 ` Steven Rostedt
2021-09-11 22:08 ` Laurent Pinchart
2021-09-11 22:42 ` Steven Rostedt
2021-09-11 23:10 ` Laurent Pinchart
2021-09-13 11:10 ` Mark Brown
2021-09-11 22:51 ` Mauro Carvalho Chehab
2021-09-11 23:22 ` Mauro Carvalho Chehab
2021-09-11 10:31 ` Leon Romanovsky
2021-09-11 11:41 ` Laurent Pinchart
2021-09-11 12:04 ` Leon Romanovsky
2021-09-11 22:04 ` Laurent Pinchart
2021-09-12 4:27 ` Leon Romanovsky
2021-09-12 7:26 ` Greg KH
2021-09-12 8:29 ` Leon Romanovsky
2021-09-12 13:25 ` Greg KH
2021-09-12 14:15 ` Leon Romanovsky
2021-09-12 14:34 ` Greg KH
2021-09-12 16:41 ` Laurent Pinchart
2021-09-12 20:35 ` Dave Airlie
2021-09-12 20:41 ` Dave Airlie
2021-09-12 20:49 ` Daniel Vetter
2021-09-12 21:12 ` Dave Airlie
2021-09-12 22:51 ` Linus Walleij
2021-09-12 23:15 ` Dave Airlie
2021-09-13 13:20 ` Arnd Bergmann
2021-09-13 13:54 ` Daniel Vetter
2021-09-13 22:04 ` Arnd Bergmann
2021-09-13 23:33 ` Dave Airlie
2021-09-14 9:08 ` Arnd Bergmann
2021-09-14 9:23 ` Daniel Vetter
2021-09-14 10:47 ` Laurent Pinchart
2021-09-14 12:58 ` Arnd Bergmann
2021-09-14 19:45 ` Daniel Vetter
2021-09-14 15:43 ` Luck, Tony
2021-09-13 14:52 ` James Bottomley
2021-09-14 13:07 ` Linus Walleij
2021-09-13 14:03 ` Mark Brown
2021-09-12 15:55 ` Laurent Pinchart
2021-09-12 16:43 ` James Bottomley
2021-09-12 16:58 ` Laurent Pinchart
2021-09-12 17:08 ` James Bottomley
2021-09-12 19:52 ` Dave Airlie
2021-09-12 7:46 ` Mauro Carvalho Chehab
2021-09-12 8:00 ` Leon Romanovsky
2021-09-12 14:53 ` Laurent Pinchart
2021-09-12 15:41 ` Mauro Carvalho Chehab
2021-09-10 23:46 ` Laurent Pinchart
2021-09-11 0:38 ` Mauro Carvalho Chehab
2021-09-11 9:27 ` Laurent Pinchart
2021-09-11 22:33 ` Mauro Carvalho Chehab
2021-09-13 12:04 ` Mark Brown
2021-09-12 19:13 ` Dave Airlie
2021-09-12 19:48 ` Laurent Pinchart
2021-09-13 2:26 ` Dave Airlie
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