Bug#910846: X server "Segmentation fault at address 0x0" when using

[Gong S.]

Package: xserver-xorg-video-radeon
Version: 1:18.1.0-1

I am using a standalone AMD HD 7670. "firmware-amd-graphics" is installed and loaded during boot.
It seems that whenever I tries to query information about hardware acceleration, X segfaults.
"dmesg" does not show any error or warning after segfault.
Sometimes other programs or games trigger it as well, with the same problem described in the file Xorg.0.log.

[Michel Dänzer]

Post by Gong S.
Package: xserver-xorg-video-radeon
Version: 1:18.1.0-1
I am using a standalone AMD HD 7670. "firmware-amd-graphics" is installed and loaded during boot.
It seems that whenever I tries to query information about hardware acceleration, X segfaults.
"dmesg" does not show any error or warning after segfault.
Sometimes other programs or games trigger it as well, with the same problem described in the file Xorg.0.log.

[...]

Post by Gong S.
[ 324.505] (EE) 0: /usr/lib/xorg/Xorg (OsLookupColor+0x139) [0x562764468de9]
[ 324.505] (EE) 1: /lib/x86_64-linux-gnu/libpthread.so.0 (funlockfile+0x50) [0x7f100883292f]
[ 324.506] (EE) 2: /usr/lib/xorg/modules/drivers/radeon_drv.so (_init+0x1592) [0x7f10073d4b24]
[ 324.506] (EE) 3: /usr/lib/xorg/Xorg (dri3_send_open_reply+0x55d) [0x562764438b4d]
[ 324.506] (EE) 4: /usr/lib/xorg/Xorg (drm_format_for_depth+0x93b) [0x56276443827b]
[ 324.506] (EE) 5: /usr/lib/xorg/Xorg (SendErrorToClient+0x35e) [0x56276430a97e]
[ 324.506] (EE) 6: /usr/lib/xorg/Xorg (InitFonts+0x3b6) [0x56276430e906]
[ 324.506] (EE) 7: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xe7) [0x7f1008683b17]
[ 324.506] (EE) 8: /usr/lib/xorg/Xorg (_start+0x2a) [0x5627642f867a]
[ 324.506] (EE)
[ 324.506] (EE) Segmentation fault at address 0x0

Please make sure the xserver-xorg-video-radeon-dbgsym and
xserver-xorg-core-dbgsym packages are installed, and either get a
backtrace with gdb or another log file.


Does the problem also happen without Option "AccelMethod" "EXA"? That's
the default and recommended configuration for your GPU.

[Michel Dänzer]

There is no "xserver-xorg-video-radeon-dbgsym" or
"xserver-xorg-core-dbgsym" in the repo.

They're in a separate repository:

deb https://deb.debian.org/debian-debug/ <suite>-debug main contrib non-free

Replace <suite> with the name of the suite you're using in your main
repository entry.

[Michel Dänzer]

Option "DRI" "3"

If removing

Option "AccelMethod" "EXA"

as well also works, that would be the best solution for you.

So it is my fault. Sorry.

The crash is still a bug, even though EXA & DRI3 isn't recommended,
because it can't work correctly in some cases.

Any chance you can test if the attached patch fixes the crash?

[Michel Dänzer]

Using "glamor" instead of "EXA" works. However, the manpage says "EXA
(for pre-TAHITI GPUs) and glamor (for R300 or higher)". TURKS GPUs
are pre-TAHITI ones.

They're also post-R300. :) The next sentence (with side note which
doesn't apply here elided) in the manpage is:

The default is glamor with R600 or newer [...], otherwise EXA.

I cannot test the patch for you.

No problem. I'll send out the patch for review anyway, it's pretty
likely it'll fix the crash.

[Gong S.]

Here is the output of GDB.
I am no developer, thus I do not know whether this is what you want.