Segfault in modesetting_drv.so on startup with hybrid Intel+AMD (Linux 6.19, XLibre 1.25.0)

[S488U]

Select the version

25.0.0.X

Describe your issue

I am not an expert in X/graphics internals, but I tried my best to debug this before reporting.

On Linux 6.19, XLibre crashes during startup with SIGSEGV when my Intel iGPU + AMD dGPU are both active.

The crash is in modesetting_drv.so during InitOutput (null pointer address 0x0).

From log:

• modeset(0): using drv /dev/dri/card1 (Intel)
• modeset(G0): using drv /dev/dri/card0 (AMD)
• Applying OutputClass "AMDgpu" options to /dev/dri/card0
• then Caught signal 11 (Segmentation fault). Server aborting

Steps to reproduce

1. Boot Arch Linux with kernel 6.19.6-arch1-1.
2. Use kernel cmdline with AMD enabled (includes amdgpu.si_support=1 and amdgpu.cik_support=1, without modprobe.blacklist=amdgpu).
3. Start XLibre.
4. X crashes with SIGSEGV in modesetting_drv.so.

What did you expect?

XLibre should start normally on hybrid Intel+AMD hardware without crashing.

Additional Information

Environment:

• Distro: Arch Linux
• XLibre: 1.25.0
• Kernel: 6.19.6-arch1-1 (issue reproduced here)
• GPUs:
  • Intel HD 520 (8086:1916)
  • AMD dGPU (1002:6660, Sea Islands)

What I tried (did not fix):

• cleaned duplicate Device sections in /etc/X11/xorg.conf.d
• removed extra options (DRI, PrimaryGPU)
• added AutoAddGPU off

Workaround:

• Boot with modprobe.blacklist=amdgpu (Intel-only path) and X starts normally.

I can attach:
Tried many times and these are the logs at each time

• xserver-1.log
• xserver-2.log
• xserver-3.log
• journalctl -b excerpts

xserver-1.log
xserver-2.log
xserver-3.log
xlibre-journal-excerpt-crash-window.txt

Extra fields

• I have checked the existing issues
• I have read the Contributing Guidelines
• I'd like to work on this issue

[S488U]

@stefan11111 @metux

[stefan11111]

Can you post a backtrace with symbols?

[S488U]

Can you post a backtrace with symbols?

Sorry. I tried to do backtrace the issue using AI's help and I couldn't find it actually. It still shows the xserver-3.log error.
And I am not an expert in this.

But I tried to find the cause by building locally and running these commands in build dir ./hw/xfree86/Xorg but it gives blank screen.

 sabbu  …/xserver/build   master !    v15.2.1   09:31 PM   
  
 sudo mkdir -p /var/local/log  
sudo chown root:root /var/local/log  
  
 sabbu  …/xserver/build   master !    v15.2.1   09:31 PM   
  
 sudo ./hw/xfree86/Xorg :1  
  
XLibre X Server 1.25.1  
X Protocol Version 11, Revision 0  
Current Operating System: Linux ArchLinux 6.19.8-arch1-1 #1 SMP PREEMPT_DYNAMIC Sat, 14 Mar 2026 01:07:43 +0000 x86_64  
Kernel command line: initrd=\intel-ucode.img initrd=\initramfs-linux.img root=PARTUUID=2ff219d2-78d2-4ab4-b863-483ff6b7ac9a zswap.enabled=0 rw rootfstype=ext4 modprobe.blacklist=tpm,tpm_tis,tpm_crb,tpm_tis_core loglevel=3 i915.enable_guc=0 i915.enable_psr=0 usbcore.autosuspend=-1                    Current version of pixman: 0.46.4  
Markers: (--) probed, (**) from config file, (==) default setting,  
(++) from command line, (!!) notice, (II) informational,  
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.  
(==) Log file: "/var/local/log/Xorg.1.log", Time: Wed Mar 18 21:32:03 2026  
Converted %D/X11/%X' to /usr/local/share/X11/xorg.conf.d'  
Converted /etc/X11/%X' to /etc/X11/xorg.conf.d'  
Converted /etc/X11/%X' to /etc/X11/xorg.conf'                            Converted /etc/%X' to /etc/xorg.conf'  
Converted %P/etc/X11/%X.%H' to /usr/local/etc/X11/xorg.conf.'  
Converted %P/etc/X11/%X' to /usr/local/etc/X11/xorg.conf'  
Converted %P/lib/X11/%X.%H' to /usr/local/lib/X11/xorg.conf.'  
Converted %P/lib/X11/%X' to /usr/local/lib/X11/xorg.conf'  
(==) Using config directory: "/etc/X11/xorg.conf.d"  
(==) Using system config directory "/usr/local/share/X11/xorg.conf.d"  
OutputClass section parsed  
InputClass section parsed  
InputClass section parsed  
InputClass section parsed  
InputClass section parsed  
OutputClass section parsed  
InputClass section parsed  
Flags section parsed  
Flags section parsed  
Device section parsed  
Screen section parsed  
ACPI: OSPMOpen called  
ACPI: Opening device  
LoaderOpen(/usr/local/lib/xorg/modules/xlibre-25/extensions/libglx.so)  
LoaderOpen(/usr/local/lib/xorg/modules/xlibre-25/drivers/modesetting_drv.so)  
LoaderOpen(/usr/local/lib/xorg/modules/xlibre-25/libglamoregl.so)  
Sync Extension 3.1  
XFree86VidModeExtensionInitVidModeAddExtension  
Popen: `"/usr/bin/xkbcomp" -w 1 "-R/usr/share/X11/xkb" -xkm "-" -em1 "The XKEYBOARD keymap compiler (xkbcomp) reports:" -emp "> " -eml "Errors from xkbcomp are not fatal to the X server" "/tmp/server-1.xkm"', fp = 0x561c23451cb0  
Pclose: fp = 0x561c23451cb0  
The XKEYBOARD keymap compiler (xkbcomp) reports:  
  
> Warning:          Multiple symbols for level 1/group 1 on key <FK23>  
Using F23, ignoring XF86TouchpadOff  
Warning:          Symbol map for key <FK23> redefined  
Using last definition for conflicting fields  
Warning:          Symbol map for key <FK24> redefined  
Using last definition for conflicting fields  
Errors from xkbcomp are not fatal to the X server  
Loaded XKB keymap /tmp/server-1.xkm, defined=0x7f  
client(0): Reserved pid(2801).  
client(0): Reserved cmdname(./hw/xfree86/Xorg) and cmdargs(:1).  
input-thread: creating thread  
input-thread: InputThreadDoWork waiting for devices  

@stefan11111 I noticed that the server only works correctly when the amd driver : radeon and amdgpu are blacklisted in the kernel boot options.

when these driver are not blacklisted, xlibre crashes segmentation fault in modsetting_drv.so
blacklisting them allows the server to start normally on my intel iGPU.

[stefan11111]

A backtrace is provided by gdb.

You have to build xlibre with -O0 -ggdb3.
Then, from another machine, ssh into the machine with problems and run Xlibre (gdb --args /path/to/Xorg )
then, press r to run Xlibre under gdb, and gdb will print a backtrace with symbols when it segfaults.