I have now been running with OpenBSD 6.5 for a couple of weeks without meeting this problem again, on a fresh install. I am very careful not to crash or halt the system abruptly !
I suspect the problem may have had to do with the inteldrm driver and the EFI, as suggested by dmesg(8) : ... acpivideo0 at acpi0: GFX0 acpivout0 at acpivideo0: LCD0 cpu0: Enhanced SpeedStep 2594 MHz: speeds: 2600, 2500, 2400, 2300, 2200, 2100, 2000, 1900, 1800, 1700, 1600, 1500, 1400, 1300, 1200 MHz pci0 at mainbus0 bus 0 pchb0 at pci0 dev 0 function 0 "Intel Core 3G Host" rev 0x09 inteldrm0 at pci0 dev 2 function 0 "Intel HD Graphics 4000" rev 0x09 drm0 at inteldrm0 inteldrm0: msi inteldrm0: 1366x768, 32bpp wsdisplay0 at inteldrm0 mux 1: console (std, vt100 emulation) wsdisplay0: screen 1-5 added (std, vt100 emulation) xhci0 at pci0 dev 20 function 0 "Intel 7 Series xHCI" rev 0x04: msi, xHCI 1.0 ... vmm0 at mainbus0: VMX/EPT efifb at mainbus0 not configured error: [drm:pid0:cpt_set_fifo_underrun_reporting] *ERROR* uncleared pch fifo underrun on pch transcoder B error: [drm:pid0:intel_pch_fifo_underrun_irq_handler] *ERROR* PCH transcoder B FIFO underrun ... error: [drm:pid81698:cpt_set_fifo_underrun_reporting] *ERROR* uncleared pch fifo underrun on pch transcoder B error: [drm:pid81698:intel_pch_fifo_underrun_irq_handler] *ERROR* PCH transcoder B FIFO underrun error: [drm:pid54999:cpt_set_fifo_underrun_reporting] *ERROR* uncleared pch fifo underrun on pch transcoder B error: [drm:pid54999:intel_pch_fifo_underrun_irq_handler] *ERROR* PCH transcoder B FIFO underrun > On Thu, May 2, 2019 at 7:53 PM <openbsd.s...@0sg.net> wrote: > > > > SYMPTOM: Soon after a fresh OpenBSD install intended to use as a > > laptop / work engine, and consequently a few uses of a graphical > > session, suddenly the X session cannot start anymore : logging > > in with a correct user/passwd pair provokes a crash and restart of > > the > > X Display Manager, displaying the xdm login screen anew. > > But I can still log in xdm as root. > > > > Xorg.0.log https://pastebin.com/pZDf90TE > > xenodm.log https://pastebin.com/abjyLCyU > > dmesg.boot https://pastebin.com/T3UGucB1 (also attached) > > Hi, > > What is the contents of your ~/.xsession & ~/.xsession-errors files? > > I had this same issue, and was able to solve it by removing .xsession > or replacing it with an empty file. > > Ian > > Hi Ian, thanks for your concern. I had saved the files from my system before re-installing : sylvain:531$ cat .xsession export ENV=$HOME/.profile export LC_CTYPE=fr_FR.UTF-8 sylvain:532$ cat .xsession-errors sylvain:533$ The .xsession on my present system/home is indeed absent. Sylvain S