On Mon, Jan 12, 2009 at 14:35, Florian Echtler <[email protected]> wrote: >> > I think that this is generally done by having the framebuffer driver >> > allocate the screen to be as large as possible. Then in the xserver >> > you know that offscreen memory address is simply from the end of the >> > visible screen. >> But does the device support any form of acceleration ? If not, I'd go >> with a shadowfb approach instead (which can be pretty efficient these >> days). > I guess that depends on how you define acceleration, but it doesn't do > much in any case. What it can do is internal copying of memory blocks, > and run-length encoding of pixel data (so you could say that it supports > accelerated drawing of horizontal lines :-).
Well, the goals of "fast rendering" and "use all possible hw features" can be pretty different sometimes. If the fastest approach is shadowfb, you could just not use these hardware features. > > But can you explain "shadowfb approach" in more detail? I've seen the > phrase in the fbdrv manual already; does that mean that the X driver > maintains a copy of the framebuffer content in memory and only tries to > transmit changed regions? Yes shadowfb does just that. A couple of drivers implement it, look at nv or radeon for example. On the plus side you get a very small driver and you just have to implement a copy hook, the regions are determined by the X server for you. Stephane _______________________________________________ xorg mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/xorg
