debugging fvwm/X11

[Simon Kainz <simon@familiekainz.at>]

Hello,

I installed Debian Hurd 9.0 inside virtualbox, which works somewhat stable.

X11 works, icewm also, but i wanted to make fvwm work. Starting fvwm,
either from icewm or directly via startx dies with the following error:

(==) Log file: "/var/log/Xorg.0.log", Time: Tue Feb  7 08:45:35 2017
(==) Using system config directory "/usr/share/X11/xorg.conf.d"
xinit: XFree86_VT property unexpectedly has 0 items instead of 1
(EE)
(EE) Backtrace:
(EE) 0: /usr/lib/xorg/Xorg (xorg_backtrace+0x52) [0x81ceee2]
(EE) 1: /usr/lib/xorg/Xorg (0x8048000+0x18ae12) [0x81d2e12]
(EE) 2: /lib/i386-gnu/libc.so.0.3 (0x1275000+0x3fbd2) [0x12b4bd2]
(EE)
(EE) Bus error at address 0x2c23000
(EE)
Fatal server error:
(EE) Caught signal 10 (Bus error). Server aborting
(EE)
(EE)
Please consult the The X.Org Foundation support
         at http://wiki.x.org
 for help.
(EE) Please also check the log file at "/var/log/Xorg.0.log" for
additional information.
(EE)
(EE) Server terminated with error (1). Closing log file.
xinit: connection to X

I know this is not enough to debug this issue, so my question is: How
should i continute from here on? I really don't know how to start e.g.
x11 inside gdb to get backtraces. How should i proceed?

Regards,

Simon