On Fri, Nov 21, 2014 at 03:48:33PM +0100, Thomas Hellstrom wrote: > On 11/21/2014 03:14 PM, Chris Wilson wrote: > > On Thu, Nov 20, 2014 at 09:56:25AM +0100, Thomas Hellstrom wrote: > >> It happens on occasion that developers of generic user-space applications > >> abuse the dumb buffer API to get hold of drm buffers that they can both > >> mmap() and use for GPU acceleration, using the assumptions that dumb buffers > >> and buffers available for GPU are > >> a) The same type and can be aribtrarily type-casted. > >> b) fully coherent. > > Both (a) and (b) are true for intel and it turns out to be a requirement > > for smooth transitions from the boot splash screens into X, and relied > > upon by userspace. > > -Chris > > > > So when you say relied upon by user-space, do you mean generic > user-space or driver-specific user-space? > > With that, I mean what component is responsible for deciding that the > dumb buffer can be accelerated? The Intel xorg driver? There is no way for the driver to know it has a dumb buffer. It copies the contents of the current framebuffer onto its replacement framebuffer so that it can do a seamless switch. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
