The segfault occurs because Xephyr's attempt to bgfill its client-facing root window writes past the end of the window's image data buffer.
The write fails because Xephyr's hostx_screen_init() function is requesting an image data buffer which is too small.
The image data buffer is too small because the calculation of bytes_per_line conflicts with the calculation of the screen's bits-per-pixel.
Finally, Ajax supplied a patch six months ago that, when rebased, fixes the problem:
http://patchwork.freedesktop.org/patch/1327/
The segfault occurs because Xephyr's attempt to bgfill its client-facing root window writes past the end of the window's image data buffer.
The write fails because Xephyr's hostx_screen_init() function is requesting an image data buffer which is too small.
The image data buffer is too small because the calculation of bytes_per_line conflicts with the calculation of the screen's bits-per-pixel.
Finally, Ajax supplied a patch six months ago that, when rebased, fixes the problem:
http:// patchwork. freedesktop. org/patch/ 1327/