Re: [RFC] Deprecation and removal of the drm2 driver

On Fri, May 18, 2018 at 9:22 PM, Ben Widawsky <ben_at_bwidawsk.net> wrote:

> On 18-05-18 14:15:03, Warner Losh wrote:
> > On Fri, May 18, 2018 at 2:12 PM, Johannes Lundberg <johalun0_at_gmail.com>
> > wrote:
> >
> > >
> > >
> > > On Fri, May 18, 2018 at 9:03 PM, Warner Losh <imp_at_bsdimp.com> wrote:
> > >
> > >> On Fri, May 18, 2018 at 1:30 PM, Steve Kargl <
> > >> sgk_at_troutmask.apl.washington.edu> wrote:
> > >>
> > >> > On Fri, May 18, 2018 at 09:14:24PM +0200, Andreas Nilsson wrote:
> > >> > > On Fri, May 18, 2018, 20:00 Niclas Zeising <zeising_at_freebsd.org>
> > >> wrote:
> > >> > >
> > >> > > > I propose that we remove the old drm2 driver (sys/dev/drm2) from
> > >> > > > FreeBSD.  I suggest the driver is marked as deprecated in 11.x
> and
> > >> > > > removed from 12.0, as was done for other drivers recently.  Some
> > >> > > > background and rationale:
> > >> > > >
> > >> > > > The drm2 driver was the original port of a KMS driver to
> FreeBSD.
> > >> It
> > >> > > > was done by Konstantin Belousov to support Intel graphics
> cards, and
> > >> > > > later extended by Jean-Sébastien Pédron as well as Konstantin to
> > >> match
> > >> > > > what's in Linux 3.8.  This included unstable support from
> Haswell,
> > >> but
> > >> > > > nothing newer than that.
> > >> > > >
> > >> > > > For quite some time now we have had the
> graphics/drm-stable-kmod and
> > >> > > > graphics/drm-next-kmods which provides support for modern AMD
> and
> > >> Intel
> > >> > > > graphics cards.  These ports, together with the linuxkpi, or
> lkpi,
> > >> has
> > >> > > > made it significantly easier to port and update our graphics
> > >> drivers.
> > >> > > > Further, these new drivers cover the same drivers as the old
> drm2
> > >> > driver.
> > >> > > >
> > >> > > > What does the community think?  Is there anyone still using the
> drm2
> > >> > > > driver on 12-CURRENT?  If so, what is preventing you from
> switching
> > >> to
> > >> > > > the port?
> > >> > > >
> > >> > > > Thank you
> > >> > > > Regards
> > >> > > > --
> > >> > > > Niclas Zeising
> > >> > > > FreeBSD x11/graphics team
> > >> > > > _______________________________________________
> > >> > > > freebsd-current_at_freebsd.org mailing list
> > >> > > > https://lists.freebsd.org/mailman/listinfo/freebsd-current
> > >> > > > To unsubscribe, send any mail to "freebsd-current-unsubscribe_at_
> > >> > freebsd.org"
> > >> > > >
> > >> > >
> > >> > > Sounds good ( deprecate resp remove ). It causes more confusion
> and
> > >> > > problems and it solves nothing.
> > >> > >
> > >> >
> > >> > Check the Makefiles
> > >> >
> > >> > % more /usr/ports/graphics/drm-next-kmod/Makefile
> > >> >
> > >> > ONLY_FOR_ARCHS= amd64
> > >> > ONLY_FOR_ARCHS_REASON=  the new KMS components are only supported on
> > >> amd64
> > >> >
> > >> > Not to ia32 friendly.
> > >> >
> > >>
> > >> So do people use i386 for desktop? And need the latest KMS stuff?
> > >>
> > >
> > > Yeah I was wondering the same.. If you're running i386, do you need drm
> > > drivers? Will scfb work an i386? (probably has legacy bios and if I
> > > remember correctly, scfb is UEFI only)
> > > I do feel sorry for anyone who would have to revert back to VESA...
> > >
> > > Would it be too much trouble to move it to a port?
> > >
> >
> > If there's someone who needs it for i386, and wants to do the work and
> > maintain it, we should allow it. But the drm2 maintainers have said its
> > likely totally broken anyway.
> >
> > Warner
>
> As a long time developer in drm/i915, and newly interested in FreeBSD (ie.
> no
> history on the matter), is there some upside and/or desire to have native
> support, or is the drm-next-kmod solution good enough?
>

Given the fast evolution of graphics hardware and the amount of code in
only the AMD and Intel drivers, keep several native implementations seems
impossible, if not wasteful.
If you are referring to drm2 in the kernel, that's not much more native
than the drm kmods, it still uses a linux compatibility layer (but not as
sophisticated).

If we were to focus our effort somewhere, it should be to create a Common
Kernel Programming Interface for Linux and *BSDs, especially for DRM
drivers. Something a bit more stable that what we see in Linux today.