Originally Posted by
Remilia
So a bit of background for this thing (and also written in the patent). Games on PS4 are programmed in a way that's to the metal with a lot of assumptions to be better optimized. This way it can always guarantee that certain things will be executed in the proper amount of time. So for example Task A can take 40ns of execution and Task B can take 50ns of execution on the PS4 but to run it properly A must take precedent first before B. However with more powerful CPUs and especially changes in architecture, it is very possible that B finishes first before A and then it errors out and bad things start happening.
Now the patent itself. It's not the actual method of backwards compatibility but it does give some insight to what they're trying to do. At the moment all it is is testing software and hardware timings on a specially designed device (PS4 presumably).
"Timing testing mode" as it's referred means it's going to be changing parameters in real time like OS configuration, GPU firmware, cpu clock, cache latency, cache frequency, etc (a whole lot of stuff), to essentially see what breaks. Also the testing hardware will have extra circuits to change IPC to determine their impact. The whole point of this is to disrupt timing of process / threads by modifying basically any aspect of the device and software to record / test for errors that may occur when doing this.
What can be inferred from this is the PS5 or whatever is going to be run as x86 (well duh, granted actually seen people float ARM around for some reason) and natively run the game in a backwards compatibility mode. This means that it won't need to be recompiled, emulated or use a translation layer the latter two causing a high overhead and the former requiring man power. Backwards compatibility mode will presumably be run in which timings would align within the tolerance of the software so that it won't break due to mismatched timings. It in theory should be a more fine grained method of backwards compatibility than the PS4 Pro to PS4 is atm, which is basically disabling the 2nd GPU cluster and down clocking the CPU / GPU.
Would love to see boring Cerny make a talk about this cause it seems very interesting to me.