Xephyr :2 -host-cursor -screen 800x480x16 -dpi 96 -ac &
$ Initializing built-in extension Generic Event Extension Initializing built-in extension SHAPE Initializing built-in extension MIT-SHM Initializing built-in extension XInputExtension Initializing built-in extension XTEST Initializing built-in extension BIG-REQUESTS Initializing built-in extension SYNC Initializing built-in extension XKEYBOARD Initializing built-in extension XC-MISC Initializing built-in extension SECURITY Initializing built-in extension XINERAMA Initializing built-in extension XFIXES Initializing built-in extension RENDER Initializing built-in extension RANDR Initializing built-in extension COMPOSITE Initializing built-in extension DAMAGE Initializing built-in extension MIT-SCREEN-SAVER Initializing built-in extension DOUBLE-BUFFER Initializing built-in extension RECORD Initializing built-in extension DPMS Initializing built-in extension X-Resource Initializing built-in extension XVideo Initializing built-in extension XVideo-MotionCompensation Initializing built-in extension SELinux Initializing built-in extension GLX (EE) (EE) Backtrace: (EE) 0: Xephyr (xorg_backtrace+0x3d) [0x7fa5bd72a4bd] (EE) 1: Xephyr (0x7fa5bd5a3000+0x18b229) [0x7fa5bd72e229] (EE) 2: /lib/x86_64-linux-gnu/libpthread.so.0 (0x7fa5bc5b5000+0xfbb0) [0x7fa5bc5c4bb0] (EE) 3: /usr/lib/x86_64-linux-gnu/libpixman-1.so.0 (0x7fa5bca0f000+0x7153a) [0x7fa5bca8053a] (EE) 4: /usr/lib/x86_64-linux-gnu/libpixman-1.so.0 (0x7fa5bca0f000+0x583bf) [0x7fa5bca673bf] (EE) 5: /usr/lib/x86_64-linux-gnu/libpixman-1.so.0 (pixman_fill+0x31) [0x7fa5bca1a981] (EE) 6: Xephyr (fbFill+0x300) [0x7fa5bd63c2d0] (EE) 7: Xephyr (fbPolyFillRect+0x1a0) [0x7fa5bd653940] (EE) 8: Xephyr (0x7fa5bd5a3000+0x13edac) [0x7fa5bd6e1dac] (EE) 9: Xephyr (miPaintWindow+0x1d1) [0x7fa5bd6600a1] (EE) 10: Xephyr (miWindowExposures+0x1d5) [0x7fa5bd660975] (EE) 11: Xephyr (0x7fa5bd5a3000+0x94c2c) [0x7fa5bd637c2c] (EE) 12: Xephyr (MapWindow+0x251) [0x7fa5bd627ed1] (EE) 13: Xephyr (0x7fa5bd5a3000+0x330d0) [0x7fa5bd5d60d0] (EE) 14: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf5) [0x7fa5bad33de5] (EE) 15: Xephyr (0x7fa5bd5a3000+0x3346f) [0x7fa5bd5d646f] (EE) (EE) Segmentation fault at address 0x7fa5b8d8e000 (EE) Fatal server error: (EE) Caught signal 11 (Segmentation fault). Server aborting (EE)