Arch Linux

The bug might be upstream, I installed the same version on my x86_64 machine and I got the same output(as regular user)

$ xaos
Warning - too long text at line 484
Warning - too long text at line 490
Warning - too long text at line 724
Warning - too long text at line 1026
Warning - too long text at line 1036
Warning - too long text at line 1037
Warning - too long text at line 1040
Warning - too long text at line 1041
Warning - too long text at line 1044
Warning - too long text at line 1047
Warning - too long text at line 1053
Warning - too long text at line 1054
Warning - too long text at line 1058
Warning - too long text at line 1061
Segmentation fault (core dumped)

$ sudo xaos
Warning - too long text at line 484
Warning - too long text at line 490
Warning - too long text at line 724
Warning - too long text at line 1026
Warning - too long text at line 1036
Warning - too long text at line 1037
Warning - too long text at line 1040
Warning - too long text at line 1041
Warning - too long text at line 1044
Warning - too long text at line 1047
Warning - too long text at line 1053
Warning - too long text at line 1054
Warning - too long text at line 1058
Warning - too long text at line 1061

but with 'sudo xaos' nothing happend after the missing segfault, I had my shell back

I can't reproduce your problem, but the warnings come from using a german locale. Using anything but german and the warnings will go away. However, I am not able to reproduce your crashes, not with english, not with german locale.

You may want to recompile xaos using this:
- add options=('!strip') to PKGBUILD
- change ./configure to CFLAGS="-O0 -g" ./configure

Using that you can generate a package with debug symbols so you can use gdb to find out why it is crashing. Note that this report is a duplicate of a 3 year old bugreport that was closed as "worksforme", I also found the same bugreport on the xaos user groups, but no solution was ever found.

I had changed my locale to LANG="en_US.UTF-8" and the warnings went away.
I have never really used gdb, maybe I will find some time at the weekend to tinker with it and report back

As a quick update:
I tried to recompile with debug symbols like you said:
[...]
Compiler options:
CC : gcc
CFLAGS : -O0 -g -I/usr/include -fomit-frame-pointer -DSFFE_USING -DSFFE_CMPLX_GSL -I/home/david/build/xaos/src/xaos-3.5/src/include
LDLAGS :
LIBS : -lpng -lz -lm -laa -lX11 -lXext -L/usr/lib -lgsl -lgslcblas -lm
X_LIBS :
[...]
but when I run gdb xaos:
[...]
Reading symbols from /usr/bin/xaos...(no debugging symbols found)...done.
(gdb) run
Starting program: /usr/bin/xaos
warning: Could not load shared library symbols for linux-vdso.so.1.
Do you need "set solib-search-path" or "set sysroot"?

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff69cc5bd in __memset_sse2 () from /usr/lib/libc.so.6

I understand that the warning is only an cosmetic issue https://bugs.archlinux.org/task/30657
I have core/glibc 2.17-1 installed

sidenote: the sha1sum of the patch didn't match, so I stipped the first 2 lines until "--- src/util/png.c" and generated a new sum, patching phase went with out error:
[...]
==> Starting build()...
patching file src/util/png.c
checking build system type... x86_64-unknown-linux-gnu
[...]

What shoud I do next to hunt down the issue?

Typing "bt" in gdb would be nice, so we can see what codepath is executed.

(gdb) run
Starting program: /usr/bin/xaos
warning: Could not load shared library symbols for linux-vdso.so.1.
Do you need "set solib-search-path" or "set sysroot"?

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff69cc5bd in __memset_sse2 () from /usr/lib/libc.so.6
(gdb) bt
#0 0x00007ffff69cc5bd in __memset_sse2 () from /usr/lib/libc.so.6
#1 0x000000000049bf3c in ?? ()
#2 0x00000000004853bb in ?? ()
#3 0x000000000041bc54 in ?? ()
#4 0x000000000041bec5 in ?? ()
#5 0x000000000040b2c9 in ?? ()
#6 0x000000000040a989 in ?? ()
#7 0x00007ffff6966a15 in __libc_start_main () from /usr/lib/libc.so.6
#8 0x00000000004046d9 in ?? ()

Is this fixed in xaos-3.6-1 ?