At the firmware / driver level, fully open specifications for high performance hardware is an impossible dream.
At best, detailed documentation is a lower priority item below "make it work" and "increase performance".
At worst, it requires exposing trade secrets.
Edit: It'd probably be more productive for everyone if we set incentives and work such that the goal we want (compilers that produce code that runs optimally on Intel, AMD, and other architectures) isn't contingent on Intel writing them for non-Intel architectures. (Said somewhat curmudgeonly, because everyone complains about things like this, but also doesn't really how insanely hard and frustratingly edge-case-ridden compiler work is)
At best, detailed documentation is a lower priority item below "make it work" and "increase performance".
At worst, it requires exposing trade secrets.
Edit: It'd probably be more productive for everyone if we set incentives and work such that the goal we want (compilers that produce code that runs optimally on Intel, AMD, and other architectures) isn't contingent on Intel writing them for non-Intel architectures. (Said somewhat curmudgeonly, because everyone complains about things like this, but also doesn't really how insanely hard and frustratingly edge-case-ridden compiler work is)