What is Nucleus?

[*] Because of that, accurately emulating RSX contexts (e.g. actually mapping and using the dma_control, driver_info, report areas) is a must. What concerns rendering: OpenGL 4.3 for now, moving to 4.5 (AZDO stuff) atm. Vulkan once it's out.

Looking at development of pete's ogl2/directx psx graphic plugin, the version written in higher directx version in mind, had less hacks. It's kind of natural that higher/successive api version brings what consoles have could already. How about opengl 4.5 and higher? Does really it have some instructions/extensions that can speed up ps3 emulation, or make ps3 instructions as native for pc gpu? Apparently xenia (x360 emu) developer dropped directx and requires ogl 4.5 with vulcan/dx12 eventually.
Wonder how close-to-metal api can help emulation, since emulator is not regular PC game. The tradition is that emulator is cpu power bound, not api overhead bound, isnt it?

Wonder how close-to-metal api can help emulation

You're wondering how an emulator that is attempting to emulate what runs on metal can benefit from a "close-to-the-metal" API? Hmm, I wonder.

Well, good tries like gopalsr83, showed that devs can do good recompilers even these are unfinished. Games were quite fast on regular pc's, what speed we can expect when used even more advanced recopliers...

Lets seee; all about pcsx2 speed is about having good cpu (intel - boring...). Dolphin devs struggles about cpu speed - lately some girls's devs take care about cpu jit ideas; cpu jit is going to speed up dolphin, while improving gpu plugin makes more compatibility (less glitches) {Edit: Actually going higher in Opengl Versions and make use of it, makes also less glitches}. PPSSPP - the most advanced emulator today - devs stick to opengl2/dx9 and opengl es 2.0. Never heard of driver overhead limitations, nor implementing ogl es 3.0/opengl 4.x or anything above.

Let me understand correctly: PR deparpment shows that: more close-to-metal means better draws-per-second improvements than previous gpu API. RPCS3 and xenia step in new area. If more dps's really helps emulation of new consoles, then go for it!

@darkf: Yeah Vulkan is pretty close to https://developer.apple.com/metal/

How much? I've only seen that it's heavily based on amd's mantle (which is not surprising considered amd "donated" all it's developments in this field to Khronos).