> -----Original Message----- > From: Adam Jackson [mailto:a...@nwnk.net] > Sent: Wednesday, October 07, 2009 8:04 AM > To: McDonald, Michael-p7438c > Cc: xorg@lists.freedesktop.org > Subject: RE: Intel Q35/Q45 fb driver? > > On Tue, 2009-10-06 at 14:04 -0700, McDonald, Michael-p7438c wrote: > > > > > Which is pretty dire. You could just run the app in the vm > > > > > but display on the host's X server > > > > > > > > Nope, that would violate security requirements for separation. > > > > > > Then I have trouble understanding how a framebuffer driver > > > would make it any better. > > > > The frame buffer driver has nothing to do with security. It is hoped > > that it will improve performance. Having multiple single > level shared > > memory regions, one per guest, is the core of the security model. > > I don't see how it would improve performance either. Which memcpy > would it let you elide?
Currently, the pixels are copied 3 times using XPutImage: shared memory -> kernel kernel -> Xorg Xorg -> frame buffer Using MIT SHM extension requires 2 copies (memcpy, XShmPutImage): shared memory -> MITSHM MITSHM -> frame buffer Being able to mmap the frame buffer directly reduces it to 1 copy (XShmPutImage): shared memory -> frame buffer Modifying MITSHM to use mmap also reduces it to 1 copy as we can then mmap our shared memory regions directly into the X server. This is probably what we'll end up doing (it's implemented and just waiting for testing). But using the X server still creates extra overhead due to its size. Since all we're doing is bitblits, the majority of X functionality is unused. Mike McDonald _______________________________________________ xorg mailing list xorg@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/xorg