I cannot seem to find the definition and/or the address of the- GTDRIVER_MAILBOX_DATA0 register in the PRM, this is true with the latest version of the PRM for that generation. I've used multiple search tools including the advanced search in Adobe acrobat reader and the recoll program. Judging by the definitions for 'GTDRIVER_MAILBOX_DATA1', and 'GTDRIVER_MAILBOX_INTERFACE', there seems to be a 4 byte gap between them where the register could be. I also looked in the Linux kernel (specifically, I found definitions: 'GEN6_PCODE_DATA' and 'GEN6_PCODE_DATA1' in i915_regs.h under- /drivers/gpu/drm/i915), it seems to also hint at the register being there.
However, because this is my first time doing anything like this, I wanted to make sure, Is this actually where the register is located? If it's located somewhere else, where is it? Thank you very much for your time and effort.
