i915: Unable to start Sway

[centromere]

Describe the bug
I am unable to start Sway. Some troubleshooting was performed in this thread, but I am not experienced enough with the FreeBSD kernel to understand what my next steps ought to be.

FreeBSD version

FreeBSD logos 15.0-CURRENT FreeBSD 15.0-CURRENT #2 drm-related-linuxkpi-changes-n279098-fac501fff97e: Mon Jul 28 13:50:04 EDT 2025     root@logos:/usr/obj/usr/src/amd64.amd64/sys/GENERIC amd64 1500054 1500048

PCI Info

pciconf -lv

hostb0@pci0:0:0:0:	class=0x060000 rev=0x05 hdr=0x00 vendor=0x8086 device=0x7d30 subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    class      = bridge
    subclass   = HOST-PCI
vgapci0@pci0:0:2:0:	class=0x030000 rev=0x00 hdr=0x00 vendor=0x8086 device=0x7d41 subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    device     = 'Arrow Lake-U [Intel Graphics]'
    class      = display
    subclass   = VGA
none0@pci0:0:4:0:	class=0x118000 rev=0x05 hdr=0x00 vendor=0x8086 device=0x7d03 subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    device     = 'Meteor Lake-P Dynamic Tuning Technology'
    class      = dasp
pcib1@pci0:0:6:0:	class=0x060400 rev=0x00 hdr=0x01 vendor=0x8086 device=0x774d subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    class      = bridge
    subclass   = PCI-PCI
pcib2@pci0:0:7:0:	class=0x060400 rev=0x10 hdr=0x01 vendor=0x8086 device=0x7ec4 subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    device     = 'Meteor Lake-P Thunderbolt 4 PCI Express Root Port'
    class      = bridge
    subclass   = PCI-PCI
none1@pci0:0:8:0:	class=0x088000 rev=0x00 hdr=0x00 vendor=0x8086 device=0x774c subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    class      = base peripheral
none2@pci0:0:10:0:	class=0x118000 rev=0x01 hdr=0x00 vendor=0x8086 device=0x7d0d subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    device     = 'Meteor Lake-P Platform Monitoring Technology'
    class      = dasp
none3@pci0:0:11:0:	class=0x120000 rev=0x05 hdr=0x00 vendor=0x8086 device=0x7d1d subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    device     = 'Meteor Lake NPU'
    class      = processing accelerators
    subclass   = processing accelerators
xhci0@pci0:0:13:0:	class=0x0c0330 rev=0x10 hdr=0x00 vendor=0x8086 device=0x7ec0 subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    device     = 'Meteor Lake-P Thunderbolt 4 USB Controller'
    class      = serial bus
    subclass   = USB
none4@pci0:0:13:2:	class=0x0c0340 rev=0x10 hdr=0x00 vendor=0x8086 device=0x7ec2 subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    device     = 'Meteor Lake-P Thunderbolt 4 NHI'
    class      = serial bus
    subclass   = USB
xhci1@pci0:0:20:0:	class=0x0c0330 rev=0x00 hdr=0x00 vendor=0x8086 device=0x777d subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    class      = serial bus
    subclass   = USB
none5@pci0:0:20:2:	class=0x050000 rev=0x00 hdr=0x00 vendor=0x8086 device=0x777f subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    class      = memory
    subclass   = RAM
iwlwifi0@pci0:0:20:3:	class=0x028000 rev=0x00 hdr=0x00 vendor=0x8086 device=0x7740 subvendor=0x8086 subdevice=0x4090
    vendor     = 'Intel Corporation'
    class      = network
ig4iic0@pci0:0:21:0:	class=0x0c8000 rev=0x00 hdr=0x00 vendor=0x8086 device=0x7778 subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    device     = 'Arrow Lake-H [Serial IO I2C Host Controller]'
    class      = serial bus
ig4iic1@pci0:0:21:3:	class=0x0c8000 rev=0x00 hdr=0x00 vendor=0x8086 device=0x777b subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    device     = 'Arrow Lake-H [Serial IO I2C Host Controller]'
    class      = serial bus
none6@pci0:0:22:0:	class=0x078000 rev=0x00 hdr=0x00 vendor=0x8086 device=0x7770 subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    class      = simple comms
pcib3@pci0:0:28:0:	class=0x060400 rev=0x00 hdr=0x01 vendor=0x8086 device=0x773c subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    class      = bridge
    subclass   = PCI-PCI
none7@pci0:0:30:0:	class=0x078000 rev=0x00 hdr=0x00 vendor=0x8086 device=0x7725 subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    device     = 'Arrow Lake-H [PCH Serial IO UART Host Controller]'
    class      = simple comms
isab0@pci0:0:31:0:	class=0x060100 rev=0x00 hdr=0x00 vendor=0x8086 device=0x7703 subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    class      = bridge
    subclass   = PCI-ISA
hdac0@pci0:0:31:3:	class=0x040100 rev=0x00 hdr=0x00 vendor=0x8086 device=0x7728 subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    class      = multimedia
    subclass   = audio
none8@pci0:0:31:4:	class=0x0c0500 rev=0x00 hdr=0x00 vendor=0x8086 device=0x7722 subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    class      = serial bus
    subclass   = SMBus
none9@pci0:0:31:5:	class=0x0c8000 rev=0x00 hdr=0x00 vendor=0x8086 device=0x7723 subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Intel Corporation'
    class      = serial bus
nvme0@pci0:1:0:0:	class=0x010802 rev=0x01 hdr=0x00 vendor=0x1344 device=0x5425 subvendor=0x1344 subdevice=0x1100
    vendor     = 'Micron Technology Inc'
    device     = '2500 NVMe SSD (DRAM-less)'
    class      = mass storage
    subclass   = NVM
re0@pci0:44:0:0:	class=0x020000 rev=0x15 hdr=0x00 vendor=0x10ec device=0x8168 subvendor=0x1028 subdevice=0x0d64
    vendor     = 'Realtek Semiconductor Co., Ltd.'
    device     = 'RTL8111/8168/8211/8411 PCI Express Gigabit Ethernet Controller'
    class      = network
    subclass   = ethernet

DRM KMOD version
11774df

To Reproduce
Steps to reproduce the behavior: Start sway

Screenshots
If applicable, add screenshots to help explain your problem.

Additional context
Add any other context about the problem here.

[amshafer]

One thing that might be helpful is to get a trace on Linux with all the DRM debugging options you can find turned on. As we found in the other thread, work is getting submitted to the GuC processor but the submitted work never actually starts which causes the GPU hangs. It would be helpful to understand what step we are missing on BSD.

See something like this

[centromere]

Thank you for the suggestion, @amshafer. There is no drm directory in /sys/modules, but I was able to get some debugging info by adding the following lines to my /boot/loader.conf file:

hw.dri.__drm_debug="-1"
dev.drm.__drm_debug="-1"
compat.linuxkpi.drm_debug="-1"

dmesg.txt

Is the information contained in the file above helpful?

[amshafer]

That's similar to the logging I have enabled. I was saying it would be helpful if we could get equivalent logging on Linux to compare it with. Linux will have the /sys/modules path.

[centromere]

I booted in to the Linux 6.8.0-71-generic kernel with the command line argument drm.debug=0x19f and obtained the following output:

dmesg.txt.gz