[Intel-gfx] Regarding report amount of usable graphics memory

[Chris Wilson]

On Wed, Nov 27, 2013 at 06:03:16PM +0000, Zhang, Jianhong wrote:
>    Hi Daniel,
> 
>     
> 
>    I’m working on a sighting that filed by PCCG. It complains that “Memory
>    usable by graphics device = 2048M” even TOLUD is 1.5GB.
> 
>    From the formula, looks like it shouldn’t affected by TOLUD size, but I
>    need the confirmation to resolve the sighting as expected.

Perhaps what they mean is that we always program the GTT to the maximum
possible size irrespective of the number of physical pages present in
the system. (Note that TOLUD is itself irrelevant since the GPU is not
restricted to lower memory.) As you have seen what we report is simply
what the hardware is programmed to, which is orthogonal to the amount of
memory present on the system (and so there is no conflict in reporting
that the GPU could address up to 2GiB of pages even if there is only
1GiB of RAM installed).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre