I was in too much of a hurry yesterday and didn't include some useful information about shmfb clients.
To make use of the framebuffer the client needs to know its details. It also needs to be able to send keyboard and mouse events to the guest and to receive information about updates to the guest's display. When a UML kernel uses a shared memory framebuffer it creates the file ~/<name>/shmid. This contains the id of the shared memory segment and the dimensions of the display (width, height and depth). It also sets up a socket to enable communication between host and guest. This is based on the way mconsole works, but with a much simplified protocol that's tailored to the needs of the framebuffer. The host sends information about keyboard and mouse events to the guest. It can also request information from the guest as to which areas of the framebuffer have been updated. This latter point is something of a limitation: the client has to poll for updates. Furthermore, there's nothing to prevent more than one client from connecting to the same guest. The guest doesn't keep track of its clients separately, so the clients won't be informed about all updates. A workaround for that would be to have the clients just update the whole display, whether or not anything has changed. But that's inefficient. A proper fix for these issues is to have the kernel track client connections and send updates without prompting. The rate at which the clients update their displays can be controlled with the --fps option, which sets the number of frames per second. The default is 10fps. The X client requires the MIT-SHM extension in the host X server. The format of the framebuffer memory must match that of a shared memory image in the host X server. So if you have a 16-bit display you need to specify a framebuffer depth of 2 bytes per pixel to use the X client. Ron ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
