GuC WOPCM question

[maksym at wezdecki.pl]

Hi,

I understand that GuC is 32bit uController, so it has access only to 4GB GTT.

I don't understand WOPCM and GTT conjunction.

>From i915 doc we can see that:
   +===========> +====================+ <== FFFF_FFFF
   ^             |      Reserved      |
   |             +====================+ <== GUC_GGTT_TOP
   |             |                    |
   |             |        DRAM        |
  GuC            |                    |
Address    +===> +====================+ <== GuC ggtt_pin_bias
 Space     ^     |                    |
   |       |     |                    |
   |      GuC    |        GuC         |
   |     WOPCM   |       WOPCM        |
   |      Size   |                    |
   |       |     |                    |
   v       v     |                    |
   +=======+===> +====================+ <== 0000_0000

Can the range of (from 0x0000_0000 to "GuC ggtt_pin_bias") be used by other parts of the KMD? Or this range is reserved only for GuC WOPCM and shouldn't be used by KMD driver for other allocations?

Thanks for reply,
Maksym