On Mon, 2009-06-22 at 17:24 -0700, Linus Torvalds wrote: > > On Tue, 23 Jun 2009, Benjamin Herrenschmidt wrote: > > > > As far as I can remember, all fbdev operations are done under the > > console semaphore. > > Yeah, and some of them are horribly broken (ie copying data from user > space while doing it - causing horrible things like VC switching latencies > and invisible printk's if an oops happens during the op). > > Or maybe that got fixed.
Well, it does rely on userspace behaving.. ie, no accel ops are done by the kernel in KD_GRAPHICS and userspace is -supposed- to switch to KD_GRAPHICS before touching the fb. In fact, nowdays, we do have the infrastructure to be smart and enforce that. IE. Instead of using a boring remap_page_ranges() in fb_mmap() we could use a fault handler. When in KD_TEXT, we fail them, when in KD_GRAPHICS, we service them, and we unmap_mapping_range() when switching. Something like that... Dunno how that interacts with the new DRM thingy though. Cheers, Ben. ------------------------------------------------------------------------------ Are you an open source citizen? Join us for the Open Source Bridge conference! Portland, OR, June 17-19. Two days of sessions, one day of unconference: $250. Need another reason to go? 24-hour hacker lounge. Register today! http://ad.doubleclick.net/clk;215844324;13503038;v?http://opensourcebridge.org -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
