From a7ebf7b457db9c7a6c9aab80f93dcf9e64af9144 Mon Sep 17 00:00:00 2001
From: Paul Menzel <pmenzel@molgen.mpg.de>
Date: Wed, 14 Oct 2026 14:38:56 +0200
Subject: [PATCH 1/3] nvidiactl: Only create device nodes if NVIDIA controllers
 are counted

`N` is the result of an arithmetic expansion, so it is never empty, and
`[ ! -z $N ]` is always true.  Even with zero counted controllers,
/dev/nvidiactl is created and nvidia-uvm, nvidia-modeset and nvidia-drm
are loaded:

    $ N=$(( 0 + 0 )); if [ ! -z $N ]; then echo "taken, N=$N"; fi
    taken, N=0

Test for a positive count instead.

Assisted-by: claude-opus-5.5 (Claude Code)
---
 nvidiactl/nvidiactl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/nvidiactl/nvidiactl b/nvidiactl/nvidiactl
index 7944b08..d791136 100755
--- a/nvidiactl/nvidiactl
+++ b/nvidiactl/nvidiactl
@@ -82,7 +82,7 @@ NVDEVS=$(lspci | grep -i NVIDIA)
 N3D=$(echo "$NVDEVS" | grep "3D controller" | wc -l)
 NVGA=$(echo "$NVDEVS" | grep "VGA compatible controller" | wc -l)
 N=$(( $N3D + $NVGA ))
-if [ ! -z $N ]; then
+if [ $N -gt 0 ]; then
   N=$(( $N - 1 ))
   for i in $(seq 0 $N); do
    mknod -m 666 /dev/nvidia$i c 195 $i

From 600ba7365019dd68b6ccb02003daf4ccac9da277 Mon Sep 17 00:00:00 2001
From: Paul Menzel <pmenzel@molgen.mpg.de>
Date: Wed, 14 Oct 2026 14:39:08 +0200
Subject: [PATCH 2/3] nvidiactl: Replace existing device nodes

`mknod` fails if the node already exists, for example when the service
is restarted:

    mknod: /dev/nvidiactl: File exists

Add the helper `make_chardev`, which removes an existing node before
creating it.  Recreating it, instead of skipping it, also makes sure
the node has the current major number, which is assigned dynamically
for nvidia-uvm.

Assisted-by: claude-opus-5.5 (Claude Code)
---
 nvidiactl/nvidiactl | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/nvidiactl/nvidiactl b/nvidiactl/nvidiactl
index d791136..4ff6a19 100755
--- a/nvidiactl/nvidiactl
+++ b/nvidiactl/nvidiactl
@@ -16,6 +16,12 @@ use_nouveau () {
   exit 1
 }
 
+# Replace an existing node, for example from an earlier run of the service.
+make_chardev () {
+  rm -f "$1"
+  mknod -m 666 "$1" c "$2" "$3"
+}
+
 if [ -d /sys/module/nouveau ] ; then
   echo >&2 "NOTE: nouveau driver loaded already, using 'mxgfx-generic'."
   set_generic_mxgfx_link
@@ -85,16 +91,16 @@ N=$(( $N3D + $NVGA ))
 if [ $N -gt 0 ]; then
   N=$(( $N - 1 ))
   for i in $(seq 0 $N); do
-   mknod -m 666 /dev/nvidia$i c 195 $i
+   make_chardev /dev/nvidia$i 195 $i
   done
-  mknod -m 666 /dev/nvidiactl c 195 255
+  make_chardev /dev/nvidiactl 195 255
 
   # CUDA
   if [ -e ${nvlink}/nvidia-uvm.ko ]; then
     insmod ${nvlink}/nvidia-uvm.ko
     D=$(grep nvidia-uvm /proc/devices | awk '{print $1}')
     if [ ! -z $D ]; then
-      mknod -m 666 /dev/nvidia-uvm c $D 0
+      make_chardev /dev/nvidia-uvm $D 0
     fi
   fi
   test -e  ${nvlink}/nvidia-modeset.ko && insmod ${nvlink}/nvidia-modeset.ko

From adf974bac4223467eb7cc5159a81b2ead9b7a13d Mon Sep 17 00:00:00 2001
From: Paul Menzel <pmenzel@molgen.mpg.de>
Date: Wed, 14 Oct 2026 14:39:19 +0200
Subject: [PATCH 3/3] nvidiactl: Do not reuse nvver for the PCI ID

The variable `nvver` first holds the PCI ID of the first NVIDIA card,
and is later reused for the driver version.  Store the PCI ID in
`pciid` instead.

Also, fill the array with `mapfile` instead of word splitting, which
shellcheck warns about:

    In nvidiactl/nvidiactl line 29:
    nvidiacards=( $(lspci -n | grep " 030[0,2]: 10de:" | cut -d ' ' -f 3) )
                  ^-- SC2207 (warning): Prefer mapfile or read -a to split command output (or quote to avoid splitting).

While at it, quote the variable in the emptiness test.

Assisted-by: claude-opus-5.5 (Claude Code)
---
 nvidiactl/nvidiactl | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/nvidiactl/nvidiactl b/nvidiactl/nvidiactl
index 4ff6a19..1a3cfbc 100755
--- a/nvidiactl/nvidiactl
+++ b/nvidiactl/nvidiactl
@@ -32,17 +32,17 @@ PCIIDHINT_DIR=/usr/share/nvidia/pciidhints
 
 kver=$(uname -r)
 
-nvidiacards=( $(lspci -n | grep " 030[0,2]: 10de:" | cut -d ' ' -f 3) )
+mapfile -t nvidiacards < <(lspci -n | grep " 030[0,2]: 10de:" | cut -d ' ' -f 3)
 
-nvver=${nvidiacards[0]}
+pciid=${nvidiacards[0]}
 
-if [ -z ${nvver} ] ; then
+if [ -z "${pciid}" ] ; then
   echo >&2 "WARNING: no nvidia card found.."
   set_generic_mxgfx_link
   exit 0
 fi
 
-pciids="${PCIIDHINT_DIR}/${kver}-${nvver} ${PCIIDHINT_DIR}/${nvver}"
+pciids="${PCIIDHINT_DIR}/${kver}-${pciid} ${PCIIDHINT_DIR}/${pciid}"
 
 for leglvlhint in ${pciids} ; do
   if [ -h "${leglvlhint}" ] ; then