Bug#906903: nvidia-driver: broken(?) dependencies

[Vincent McIntyre]

On a system where I have been successfully mixing stable & backports
I hit the same dependency problem. So I think this is a recent change.
I tried to dig a bit further to see if I could flush out the cause.

TL;DR libegl1-glvnd-nvidia, which I previously installed from backports,
      is only in stable and not (any longer) in stretch-backports.

Does this imply the dependencies of the backported nvidia-egl-icd
need to be tweaked (drop libegl1-glvnd-nvidia)?

Gory details:

# apt -t stretch-backports install nvidia-egl-icd
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 nvidia-egl-icd : Depends: libegl1 (>= 0.2.999) but it is not going to be installed or
                           libegl1-glvnd-nvidia but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

# apt-cache show nvidia-egl-icd | grep Depend | sed -e 's/, /\n/g'
Depends: nvidia-egl-common
libegl1 (>= 0.2.999) | libegl1-glvnd-nvidia
libegl-nvidia0 (= 390.77-1~bpo9+1)
Depends: nvidia-egl-common
libegl1xxx (>= 0.2.999) | libegl1-glvnd-nvidia
libegl-nvidia0 (= 390.48-2~bpo9+3)
Depends: nvidia-egl-common
libegl1 (>= 0.2.999) | libegl1-glvnd-nvidia
libegl-nvidia0 (= 384.130-1)

# dpkg -l libegl1 libegl-nvidia0 
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                   Version          Architecture     Description
+++-======================-================-================-=================================================
ii  libegl-nvidia0:amd64   390.48-2~bpo9+3  amd64            NVIDIA binary EGL library
un  libegl1                <none>           <none>           (no description available)

# dpkg -l libegl1xxx  libegl1-glvnd-nvidia
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                   Version          Architecture     Description
+++-======================-================-================-=================================================
ii  libegl1-glvnd-nvidia:a 390.48-2~bpo9+3  amd64            Vendor neutral GL dispatch library -- libEGL
un  libegl1xxx             <none>           <none>           (no description available)


So as a starting point I have libegl1-glvnd-nvidia installed,
instead of libegl1xxx or libegl1 (neither of which were ever installed).

It seems that for some reason apt now wants libegl1 in preference
to libegl1-glvnd-nvidia, despite the latter being the latest version.
The preferences scoring comes out like this:

# apt-cache policy libegl1
libegl1:
  Installed: (none)
  Candidate: 1.0.0+git20180308-2~bpo9+1
  Version table:
     1.0.0+git20180308-2~bpo9+1 200
        200 http://debian-archive.atnf.csiro.au:9999/debian stretch-backports/main amd64 Packages

# apt-cache policy  libegl1-glvnd-nvidia
libegl1-glvnd-nvidia:
  Installed: 390.48-2~bpo9+3
  Candidate: 390.48-2~bpo9+3
  Version table:
 *** 390.48-2~bpo9+3 100
        100 /var/lib/dpkg/status
     384.130-1 990
        990 http://debian-archive.atnf.csiro.au:9999/debian stretch/non-free amd64 Packages

So it looks like libegl1-glvnd-nvidia has been removed from the
backports suite?

I checked what explicitly installing all the packages that can be
upgraded would do, which may be of interest.

# apt --simulate -t stretch-backports install `cat upgradable`
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following additional packages will be installed:
  glx-alternative-mesa glx-alternative-nvidia glx-diversions libdrm-amdgpu1
  libdrm-common libdrm-intel1 libdrm-nouveau2 libdrm-radeon1 libdrm2 libegl1
  libegl1-mesa libgl1 libgl1-mesa-dri libgl1-mesa-glx libglapi-mesa libgles2
  libgles2-mesa libglvnd0 libglx-mesa0 libglx0 libllvm6.0 libwayland-egl1
  libwayland-egl1-mesa update-glx
Recommended packages:
  libcuda1-i386 nvidia-settings nvidia-driver-libs-i386 libopengl0
  | libopengl0-glvnd-nvidia libgles-nvidia2 nvidia-egl-wayland-icd
  nvidia-vulkan-icd
The following packages will be REMOVED:
  libegl1-glvnd-nvidia libgl1-glvnd-nvidia-glx libglvnd0-nvidia
  libglx0-glvnd-nvidia
The following NEW packages will be installed:
  libdrm-amdgpu1 libdrm-common libdrm-intel1 libdrm-nouveau2 libdrm-radeon1
  libegl1 libgl1 libgl1-mesa-dri libgles2 libglvnd0 libglx-mesa0 libglx0
  libllvm6.0 libwayland-egl1
The following packages will be upgraded:
  glx-alternative-mesa glx-alternative-nvidia glx-diversions libcuda1 libdrm2
  libegl-nvidia0 libegl1-mesa libgl1-mesa-glx libgl1-nvidia-glvnd-glx
  libglapi-mesa libgles2-mesa libglx-nvidia0 libnvidia-cfg1 libnvidia-eglcore
  libnvidia-fatbinaryloader libnvidia-glcore libnvidia-ml1
  libnvidia-ptxjitcompiler1 libwayland-egl1-mesa nvidia-alternative
  nvidia-driver nvidia-driver-bin nvidia-driver-libs nvidia-egl-icd
  nvidia-kernel-dkms nvidia-kernel-support nvidia-smi nvidia-vdpau-driver
  update-glx xserver-xorg-video-nvidia
30 upgraded, 14 newly installed, 4 to remove and 72 not upgraded.
...

Vince