Guest (post-reset, clean-source snapshot):
DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026     root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC  x86_64

GPU: virtio VGA only (vgapci0@pci0:0:2.0 class=0x030000 chip=0x11111234) -- ZERO Intel (0x8086) PCI devices
     sysctl hw.drm    -> unknown oid (no drm device attached)
     sysctl hw.backlight_level -> unknown oid (no i915 panel backlight registered)
Guest source /usr/src/sys/dev/drm/i915/intel_panel.c md5 = cfe495b2207583b24f9c7c5714b38389
Audited tree sys/dev/drm/i915/intel_panel.c   md5 = cfe495b2207583b24f9c7c5714b38389   (MATCH)

=> intel_panel.c backlight paths are hardware-gated on this guest: no Intel GPU,
   no LVDS/eDP panel, no VBT. Per family convention (DF-4022 et al.) the finding
   is source-certain / runtime-inconclusive. trigger.sh documents the exact
   command that panics a vulnerable VLV/CHV machine.