c0de said:
I mean assuming you can boot an x86 os and you have the appropriate drivers, you can apparently run x86 binaries on a ps4.
Sort of like original XBox?
Given Sony and MS both keep the isa and AMD gpus, who would expect anything different?
There's the caveat of GPUs having to maintain ISA/binary compatibility as well, which hasn't really been common for PCs since mid 80s (and even then, compatibility would apply loosely). I assume they would make sure AMD does provide the compatibility layer in any incremental upgrades, but I really wouldn't make assumptions that x86 is where the compatibility comes from.
Orayn said:
No. PS2 games on PS4 just multiply the size of the framebuffer by 2 in each direction and naively render the game at a higher resolution.
No, naive upsize of framebuffer would not work for 99% of PS2 library.
When emulating devices with UMA (or hybrid UMA, as the case was with PS2), any element in GPU write-address range is a valid computational part of final image, so hacking around by resizing main render target practically guarantees that you will render the game incorrectly. To what degree, depends on a number of other things, but with PS2 it was quite common to directly manipulate render-targets via their address-mapping (ie. eDRam was basically a giant register stack to play with) so the problems can range from visual glitches to unplayable mess. You pretty much have two options:
a) Up-size the entire addressable space of the GPU(meaning everything that gets stored, including all textures and render targets will be "higher" resolution), and then make sure the address-math is corrected for higher precision everywhere in your virtual machine.
b) Render native for 100% compatibility, and generate additional samples by subpixel-offsets and accumulation (which is what that patent-link suggests).
Former adds considerable complexity to the VM, and if you allow non-even upscales, math gets fuzzy with regards to "correct" outputs. I suspect PCSX2 is doing something like this, and results are predictably poor - virtually no PS2 game I've tried on it actually looks fully "correct" in high-res, albeit in the "good" ones, artifacts aren't offensive enough to affect playability in any meaningful way, and many come with specific-hacks to approximate the original look more closely.
The latter is more sensible way to actually
guarantee correctness/compatibility, and if you can afford it, you can render as many extra samples as naive-upsizing would. Non-integer scaling-ratios are still a problem, so it's presumably why they went with 2x2 exact.
Contrast this with emulating machines that used dedicated Framebuffer memory(like GC/Wii/DC) - where emulators get consistently better results with the "naive" approach, so to speak.