Created attachment 644162 [details]
/var/log/Xorg.0.log

xrandr tells me:

16:35 localhorse:~ > xrandr
Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
eDP1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis)
276mm x 156mm
   1920x1080     60.04*+
   1400x1050     59.98  
   1280x1024     60.02  
   1280x960      60.00  
   1024x768      60.00  
   800x600       60.32    56.25  
   640x480       59.94  
DP1 disconnected (normal left inverted right x axis y axis)
[...]

$ xrandr --output eDP1 --fb 4096x4096 --panning 4096x4096+0+0 -s 1920x1080
(success)

still works, but

$ xrandr --output eDP1 --fb 8192x8192 --panning 8192x8192+0+0 -s 1920x1080
(crashes Xorg)

[529388.419] (II) intel(0): resizing framebuffer to 4096x4096
[529388.481] (II) intel(0): switch to mode 1920x1080@60.0 on eDP1 using pipe 0,
position (2176, 3016), rotation normal, reflection none
[529388.482] (II) intel(0): switch to mode 1920x1080@60.0 on eDP1 using pipe 0,
position (0, 0), rotation normal, reflection none
[529392.350] (II) intel(0): resizing framebuffer to 8192x8192
[529392.441] (EE) 
[529392.441] (EE) Backtrace:
[529392.441] (EE) 0: /usr/bin/X (xorg_backtrace+0x48) [0x58cb48]
[529392.441] (EE) 1: /usr/bin/X (0x400000+0x190b89) [0x590b89]
[529392.441] (EE) 2: /lib64/libc.so.6 (0x7f677c658000+0x35200) [0x7f677c68d200]
[529392.441] (EE) 3: /usr/lib64/xorg/modules/drivers/intel_drv.so
(0x7f67790ef000+0x1b90d) [0x7f677910a90d]
[529392.441] (EE) 4: /usr/lib64/xorg/modules/drivers/intel_drv.so
(0x7f67790ef000+0x1cbc4) [0x7f677910bbc4]
[529392.441] (EE) 5: /usr/lib64/xorg/modules/drivers/intel_drv.so
(0x7f67790ef000+0x25310) [0x7f6779114310]
[529392.441] (EE) 6: /usr/lib64/xorg/modules/drivers/intel_drv.so
(0x7f67790ef000+0x34f59) [0x7f6779123f59]
[529392.441] (EE) 7: /usr/lib64/xorg/modules/drivers/intel_drv.so
(0x7f67790ef000+0x63323) [0x7f6779152323]
[529392.441] (EE) 8: /usr/bin/X (0x400000+0xba769) [0x4ba769]
[529392.441] (EE) 9: /usr/bin/X (ProcRRSetScreenSize+0x19b) [0x4ff42b]
[529392.441] (EE) 10: /usr/bin/X (0x400000+0x3bd8e) [0x43bd8e]
[529392.441] (EE) 11: /usr/bin/X (0x400000+0x3fb6a) [0x43fb6a]
[529392.441] (EE) 12: /lib64/libc.so.6 (__libc_start_main+0xf5)
[0x7f677c679b05]
[529392.441] (EE) 13: /usr/bin/X (0x400000+0x2b15e) [0x42b15e]
[529392.441] (EE) 
[529392.441] (EE) Bus error at address 0x7f6756000000
[529392.441] (EE) 
Fatal server error:
[529392.441] (EE) Caught signal 7 (Bus error). Server aborting

lspci:
00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated
Graphics Controller (rev 0b)
00:02.0 0300: 8086:0a16 (rev 0b)

Is some "aperture size" BIOS setting too small perhaps?