[PATCH] host/rootfs: Automatically select card node

[Demi Marie Obenour <demiobenour@gmail.com>]

This allows Weston to launch even if there if /dev/dri/card0 does not
exist.

This requires a shell script for string processing.  It could be written
in Rust, but that's not worth it for a temporary workaround.

It also prevents waiting for the card to be ready.  Instead, let s6
restart Weston over and over until Weston finally runs.

Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
---
This makes Spectrum work on my AMD system.
---
 host/rootfs/file-list.mk               |  1 +
 host/rootfs/image/etc/s6-rc/weston/run |  6 +++---
 host/rootfs/image/usr/bin/run-weston   | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/host/rootfs/file-list.mk b/host/rootfs/file-list.mk
index 3899d620717fc97f42e669e5313c4100dcf5b1cd..0ece8e08a0e2d367fe124e90896355aa98a58cb8 100644
--- a/host/rootfs/file-list.mk
+++ b/host/rootfs/file-list.mk
@@ -62,6 +62,7 @@ FILES = \
 	image/usr/bin/run-appimage \
 	image/usr/bin/run-flatpak \
 	image/usr/bin/run-vmm \
+	image/usr/bin/run-weston \
 	image/usr/bin/spectrum-update \
 	image/usr/bin/vm-console \
 	image/usr/bin/vm-import \
diff --git a/host/rootfs/image/etc/s6-rc/weston/run b/host/rootfs/image/etc/s6-rc/weston/run
index fd59586c719391deb546c29578341e16a61ed4ce..6c0aac4a2326b5d56b9c09f82589dfbcc78eaabd 100644
--- a/host/rootfs/image/etc/s6-rc/weston/run
+++ b/host/rootfs/image/etc/s6-rc/weston/run
@@ -2,7 +2,7 @@
 # SPDX-License-Identifier: EUPL-1.2+
 # SPDX-FileCopyrightText: 2021, 2025 Alyssa Ross <hi@alyssa.is>
 
-importas -Siu WAYLAND_DISPLAY
+importas -Si WAYLAND_DISPLAY
 
 piperw 4 3
 background {
@@ -40,7 +40,6 @@ redirfd -r 0 /dev/tty1
 
 importas -i home HOME
 cd $home
-if { udevadm wait /dev/dri/card0 }
 s6-setuidgid wayland
 bwrap
   # no --unshare-net, breaks udev hotplug
@@ -88,4 +87,5 @@ bwrap
   --bind /run/user/0 /run/user/0
   --bind /run/wayland /run/wayland
   --
-weston -S $WAYLAND_DISPLAY
+  elglob -w0 CARD "/dev/dri/card[0-9]*"
+  /usr/bin/run-weston $CARD
diff --git a/host/rootfs/image/usr/bin/run-weston b/host/rootfs/image/usr/bin/run-weston
new file mode 100755
index 0000000000000000000000000000000000000000..6a14f905d2e9e5533d00aac1ee7f920ebf55fac3
--- /dev/null
+++ b/host/rootfs/image/usr/bin/run-weston
@@ -0,0 +1,32 @@
+#!/usr/bin/sh --
+# SPDX-License-Identifier: EUPL-1.2+
+# SPDX-FileCopyrightText: 2026 Demi Marie Obenour <demiobenour@gmail.com>
+set -euf
+case ${1-} in
+/dev/dri/card[0-9]*)
+	first_dev=${1#/dev/dri/} extra_cards=
+	shift
+	;;
+*)
+	echo 'No card nodes found, cannot run Weston' >&2
+	exit 1
+	;;
+esac
+for i; do
+	case $i in
+	*,*) continue ;;
+	/dev/dri/card[0-9]*) : ;;
+	*)
+		echo 'Bad name from execline script' >&2
+		exit 1
+		;;
+	esac
+	card_name=${i#/dev/dri/}
+	case $card_name in */*) continue ;; esac
+	if [ -z "$extra_cards" ]; then
+		extra_cards=--additional-devices=$card_name
+	else
+		extra_cards=$extra_cards,$card_name
+	fi
+done
+exec weston --backend=drm "--drm-device=$first_dev" $extra_cards -S "$WAYLAND_DISPLAY"

---
base-commit: 4827f7591e945f331a945fb53a9fd4e8ebfdbc12
change-id: 20260523-weston-card-fix-725c98d5245f

-- 
Sincerely,
Demi Marie Obenour (she/her/hers)