Created attachment 121775 [details] Fix crashes when mastersp is NULL On a POWER8 machine under both Debian Jessie and Debian Stretch Xorg crashes on startup when using the radeon driver and a Radeon R9 290X. Kernel modesetting outside of X appears to function normally. The crash is also triggered on output change. The attached patch fixes the crashes, however nothing shows up on the HDMI port when X is started.
Created attachment 121776 [details] Fix crashes when mastersp is NULL
Please attach the Xorg log from a crash.
While I do not currently have the ability to execute X on the test system (it needs to wait for another maintenance window) this log is extremely similar, down to crashing at the same point in the randr code: https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/1463224
(In reply to Michel Dänzer from comment #2) > Please attach the Xorg log from a crash. I finally got access to the machine again for testing: https://paste.ee/p/ONT5u
Looks like Xorg falls back to the fbdev driver for the ASPEED GPU, because xf86-video-ast isn't installed. But the fbdev driver actually ends up using one of the Radeon GPUs. If you want to use the ASPEED GPU, installing xf86-video-ast might help. Otherwise, you should be able to prevent the fbdev driver from loading by creating an /etc/X11/xorg.conf with a Section "Device" for at least one of the Radeon GPUs. The patch should be sent (as a proper Git formatted patch) to the xorg-devel mailing list for review.
Fixed as of: commit 2af0a50a4bb9be9f58681d417ceb9a7029caaf3b Author: Adam Jackson <ajax@redhat.com> Date: Wed Feb 28 11:23:41 2018 -0500 randr: Fix a crash on initialization with GPU screens RRSetChanged (immediately above) was immune to screens with no master, but RRTellChanged was not: Thread 1 "X" received signal SIGSEGV, Segmentation fault. RRTellChanged (pScreen=<optimized out>) at ../../randr/randr.c:576 576 mastersp = rrGetScrPriv(master); (gdb) bt #0 RRTellChanged (pScreen=<optimized out>) at ../../randr/randr.c:576 #1 0x000055555566f1e9 in RRNoticePropertyChange (value=0x555555bfbf28, property=70, output=0x555555bfef10) at ../../ra ndr/rrproperty.c:153 #2 RRChangeOutputProperty (output=output@entry=0x555555bfef10, property=<optimized out>, type=type@entry=19, format=fo rmat@entry=32, mode=<optimized out>, mode@entry=0, len=len@entry=1, value=0x7fffffffe77c, sendevent=1, pending=0) at ../../randr/rrproperty.c:263 #3 0x000055555566dba5 in RROutputSetNonDesktop (output=output@entry=0x555555bfef10, nonDesktop=nonDesktop@entry=0) at ../../randr/rroutput.c:333 ... Reported-by: Michel Dänzer <michel@daenzer.net> Signed-off-by: Adam Jackson <ajax@redhat.com>
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