[PATCH] drm.h: Handle DragonFly like Linux

[Francois Tigeot]

On Mon, May 16, 2016 at 11:02:33PM +0100, Emil Velikov wrote:
> On 16 May 2016 at 17:24, Francois Tigeot <ftigeot at wolfpond.org> wrote:
> >
> > The #else code path is not being used on DragonFly and actually breaks
> > kernel compilation.
> >
> I guess what I'm wondering here is where they working at some point in
> the past ? What was wrong with scheme in the first place ? Surely
> things weren't that bad.

For DragonFly, this did work a long time ago when the drm kernel drivers
were very different from the Linux ones.

> Hmm are you sure about this ... looking at OpenBSD and DragonFly repos
> there seems to be no changes to drm.h. Yet again I'm looking at the
> libdrm which is should be identical to the kernel one with the former
> user space 'version'. Do you define __linux__ for user space or you
> fall back to the 'else' ?

Hrmm. I didn't think about libdrm at all, I only looked at the various
kernel headers.

> [Please tell me that you're not having two different definitions, drm
> header, of the interface on each side - kernel vs userspace]

I'm afraid we have. Kernel headers are not available to userland and
libdrm ones are provided by the libdrm package.

FreeBSD and NetBSD even have two different drm.h kernel headers. For some
reason they think it is a good idea to keep a separate drm implementation
from ~= 10 years ago or so.

> >> Alternatively if one insists on using the __linux__ route here, imho
> >> it's better to just set the define it in your build.
> >
> > It's not really possible for me to patch gcc here since some software
> > depends on the operating system not advertising itself as Linux.
> >
> That sounds quite nasty. Wouldn't it be easier and quicker to beat the
> "else" back into shape, as opposed to trying to force things ?

I guess I'll have to keep patching it out locally.
Drm drivers are developed for Linux first and foremost and I'd like to
reduce differences with upstream as much as possible.

> > On the other hand, the non-Linux code path really is unused. I didn't want
> > to be too intrusive in my patch but it's probably best to just remove it.
> >
> There is more to this world than Linux and BSD, there's Solaris as
> well. Even though they tend to be very quiet ;-)

Right. I forgot about it since the Solaris-derived source code I have easy
access to is illumos-gate and its drm.h hasn't been updated since 2009.

> TL;DR: Please don't diverge userspace vs kernel drm headers. Just beat
> it in shape so that it works in both cases (most likely the 'else'
> one).
> 
> Hopefully ^^ does not sound to hard to achieve and/or demanding ?

They are divergent by design :-/
Making the Linux headers public and removing the #else path in libdrm's
drm.h could be the right thing to do. I'll keep thinking about it...

> P.S. Perhaps we should spend an hour or so over the next XDC trying to
> flush any remaining differences/patches in the graphics stack ? Not
> sure how many BSD/Solaris people will be around though.

I'm afraid there won't be many *BSD people around. This year, the XDC and
EuroBSDCon conferences fall on the same week-end :-(
I'm not sure which one I will be attending to at this point.

Thanks Emil,

-- 
Francois Tigeot