On Tue, Aug 18, 2009 at 2:08 AM, Thomas Hellström<tho...@shipmail.org> wrote: > Kristian Høgsberg wrote: >> Perhaps TTM bo read/write could use ioctls like the gem pwrite/pread >> ioctls? The only way we can get asynchronous notifications from the >> drm to userspace is through readable events on the drm fd. How were >> you planning to implement read and write from multiple bo's through >> one fd anyway? Reusing the fake offset we use for mmap? I think the >> ioctl approach is cleaner since you can just pass in the object handle >> and the offset into the object. Maybe even add src and dst stride >> arguments. > > It's a common misconception that the TTM bo offsets are fake offsets from > outer space. > The offsets aren't fake offsets but real offsets into the device address > space, so a logical consequence of mapping a part of that address space is > to be able to read and write to the same address space, That is read / write > implemented using syscalls as intended. > > That said, rectangular bo blit ioctls is probably a good idea as well, and > some drivers, like via, already have them. > > But I do think that if we claim device reads and writes for modesetting, we > should move bo IO to another device to be consistent.
Oh, to this last paragraph I wanted to point out that the drm fd event isn't modesetting specific. It's a generic event mechanism that we can use for other cases. For example, an asynchronous glReadPixels/DownloadFromScreen ioctls, or a "breadcrumb" ioctl that sends an event back once the command processor has caught up. The event structure has a header like this: struct drm_event { __u32 type; __u32 length; }; which lets us introduce new types of events and lets an older userspace skip unknown events. cheers, Kristian ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel