bin/56452: MAKEDEV should also create /dev/dri/renderD* devices

[rvp%SDF.ORG@localhost]

>Number:         56452
>Category:       bin
>Synopsis:       MAKEDEV should also create /dev/dri/renderD* devices
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Oct 12 09:25:00 +0000 2021
>Originator:     RVP
>Release:        NetBSD/amd64 9.99.91
>Organization:
>Environment:
NetBSD x202e.localdomain 9.99.91 NetBSD 9.99.91 (MYKERNEL) #0: Tue Oct 12 08:12:37 UTC 2021  bld@x202e.localdomain:/usr/obj/sys/arch/amd64/compile/MYKERNEL amd64
>Description:
/dev/MAKEDEV drm0 drm1 etc., should also create the corresponding renderD*
devices. The mpv(1) manpage indicates that --vo=gpu,--vo=vaapi and/or
--hwdec=vaapi-copy uses these devices, and a ktrace does seem to bear
that out:

$ for f in $(ldd /usr/pkg/bin/mpv | awk '/ => / { print $3 }')
> do strings $f | fgrep dri/renderD && echo @$f
> done
/dev/dri/renderD%d
@/usr/pkg/lib/ffmpeg4/libavutil.so.56
/dev/dri/renderD
@/usr/pkg/lib/libva-drm.so.2

$ ktrace -di -tn mpv Coin\ Operated\ -\ Animated\ Short\ Film-5L4DQfVIcdg.mp4

$ kdump | fgrep /dev/dri/render
  4035   4245 mpv      NAMI  "/dev/dri/renderD128"
  4035   4245 mpv      NAMI  "/dev/dri/renderD128"
  4035   4245 mpv      NAMI  "/dev/dri/renderD129"
  4035   4245 mpv      NAMI  "/dev/dri/renderD129"
  4035   4245 mpv      NAMI  "/dev/dri/renderD130"
  4035   4245 mpv      NAMI  "/dev/dri/renderD130"
  4035   4245 mpv      NAMI  "/dev/dri/renderD131"
  4035   4245 mpv      NAMI  "/dev/dri/renderD131"
  4035   4245 mpv      NAMI  "/dev/dri/renderD128"
  4035   4245 mpv      NAMI  "/dev/dri/renderD128"
  4035   4245 mpv      NAMI  "/dev/dri/renderD129"
  4035   4245 mpv      NAMI  "/dev/dri/renderD129"
  4035   4245 mpv      NAMI  "/dev/dri/renderD130"
  4035   4245 mpv      NAMI  "/dev/dri/renderD130"
  4035   4245 mpv      NAMI  "/dev/dri/renderD131"
  4035   4245 mpv      NAMI  "/dev/dri/renderD131"
$ 

>How-To-Repeat:
As above.
>Fix:
--- MAKEDEV.orig	2021-09-25 10:41:03.000000000 +0000
+++ MAKEDEV	2021-10-09 15:10:28.776715810 +0000
@@ -1519,8 +1519,10 @@
 
 drm[0-9]*)
 	unit=${i#drm}
+	unit2=$((unit + 128))
 	makedir dri 755
 	mkdev dri/card$unit c 180 $unit 660
+	mkdev dri/renderD${unit2} c 180 ${unit2} 660
 	;;
 
 drvctl)