How to enable software rendering via X server

[Dan Nicholson]

On Mon, Feb 14, 2011 at 11:15 PM, Neeraj N T <neerajnt at tataelxsi.co.in> wrote:
> I set LIBGL_ALWAYS_SOFTWARE=1.But the output I got was the same:
>
> direct rendering: No
> OpenGL renderer string: Mesa DRI Intel(R) IGDNG_M GEM 20091221 2009Q4

This means you also have LIBGL_ALWAYS_INDIRECT set, which means the
server is creating the GLX context. I don't think you can easily
control which dri driver the server opens, but I might be wrong. So,
if you have LIBGL_ALWAYS_SOFTWARE set and LIBGL_ALWAYS_INDIRECT unset,
then you should get direct rendering with the swrast.

To review,

LIBGL_ALWAYS_INDIRECT: use the X server's GLX context. This used to
mean you'd also get software rendering, but with AIGLX you'll probably
get the hardware DRI driver.

LIBGL_ALWAYS_SOFTWARE: tell libGL to use the software renderer. This
only works with direct rendering because otherwise you're getting the
DRI driver that the X server opened, and it's not controlled by this
variable.

--
Dan