Hi, I ran into what looks like the same issue on an old ThinkPad T60 with Intel GMA 950 graphics (945GM, PCI ID 8086:27a2).
I'm running Devuan 6 (Excalibur), with Xorg 21.1.16 and libpciaccess0 0.17-3+b3. Whenever I tried logging into XFCE through LightDM, the desktop would appear for a couple of seconds before dropping me back to the login screen. The same thing happened with SLiM. Interestingly, starting XFCE manually with startx worked fine. The Xorg crash log consistently showed: libpciaccess.so.0 (pci_device_vgaarb_set_target+0x113) Segmentation fault at address 0x30 Caught signal 11 (Segmentation fault) I tried switching the Intel driver from SNA to UXA and disabling DPMS, but neither helped, then rebuilt libpciaccess 0.17-3 with NULL checks for pci_sys in the six VGA arbitration functions mentioned in this report. After installing the patched package, I was finally able to log into XFCE normally through LightDM. The login crash is gone. So I can confirm that the workaround also works on Intel 945GM / GMA 950 hardware. I haven't tested long-term stability yet, but so far the issue appears to be resolved.
