On Sat, Sep 17, 2011 at 3:06 PM, Florian Tobias Schandinat <FlorianSchandinat@xxxxxx> wrote: > On 09/17/2011 06:23 PM, Dave Airlie wrote: >>> >>> Is it? Well, okay, I don't want to use any acceleration that can crash my >>> machine, where can I select it, preferably as compile time option? I didn't find >>> such a thing for Intel or Radeon. Don't say, I should rely on userspace here or >>> use fbdev for this. >> >> Just tell the X driver to not use acceleration, and it you won't get >> any acceleration used, then you get complete stability. If a driver >> writer wants to turn off all accel in the kernel driver, it can, its >> not an option we've bothered with for intel or radeon since it really >> makes no sense. To put it simply you don't really seem to understand >> the driver model around KMS. If no userspace app uses acceleration >> then no acceleration features will magically happen. If you want to >> write a simple app against the KMS API like plymouth you can now use >> the dumb ioctls to create and map a buffer that can be made into a >> framebuffer. Also you get hw cursors + modesetting. > > Again, you seem to not understand my reasoning. The "if" is the problem, it's > the kernels job to ensure stability. Allowing the userspace to decide whether it > crashes my machine is not acceptable to me. > I do not claim that it is impossible to write a KMS driver in a way that it does > not crash, but it seems more difficult than writing an fbdev driver. > It's perfectly valid to write a KMS DRM driver that doesn't support acceleration in which case it will be just as "stable" as a fbdev driver. In fact on modern hardware it's probably easier to write a KMS DRM driver than a fbdev driver because the API and internal abstractions match the hardware better. If you have hardware with 4 display controllers, 2 DACs, a TMDS encoder, and a DP encoder how do you decide which combination of components and modes to light up at boot using fbdev? Alternatively, if you wanted to support acceleration as well, you can add a module option to force acceleration off at the kernel level rather than from userspace. It's trivial. Alex _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
