Xephyr - X server outputting to a window on a pre-existing X display
] [option ...
is a kdrive server that outputs to a window on a pre-existing
"host" X display. Think Xnest
but with support for modern
extensions like composite, damage and randr.
which is an X proxy, i.e. limited to the capabilities of the
host X server, Xephyr
is a real X server which uses the host X server
window as "framebuffer" via fast SHM XImages.
It also has support for "visually" debugging what the server is
The server accepts all the standard options of Xserver(1) and the following
- -screen widthxheight
- sets the screen size.
- -parent id
- uses existing window id . If a -screen
argument follows a -parent argument, this screen is embedded into
the given window.
- set 'cursor acceleration': The host's cursor is reused.
This is only really there to aid debugging by avoiding server paints for
the cursor. Performance improvement is negligible.
- Allow the Xephyr window to be resized, even if not embedded
into a parent window. By default, the Xephyr window has a fixed size.
- Disable grabbing the keyboard and mouse.
Send a SIGUSR1 to the server (e.g. pkill -USR1 Xephyr) to toggle the debugging
mode. In this mode red rectangles are painted to screen areas getting painted
before painting the actual content. The delay between this can be altered by
setting a XEPHYR_PAUSE env var to a value in micro seconds.
- Rotated displays are currently updated via full blits. This
is slower than a normal orientated display. Debug mode will therefore not
be of much use rotated.
- The '-host-cursor' cursor is static in its appearance.
- The build gets a warning about 'nanosleep'. I think the
various '-D' build flags are causing this. I haven't figured as yet how to
work round it. It doesn't appear to break anything however.
- Keyboard handling is basic but works.
- Mouse button 5 probably won't work.
Matthew Allum <firstname.lastname@example.org> 2004