In the wake of recent rumors, and outrage, regarding PlayStation 4′s Direct and Flexible memory, Sony has issued an official statement about the console’s RAM debacle:
We would like to clear up a misunderstanding regarding our “direct” and “flexible” memory systems. The article states that “flexible” memory is borrowed from the OS, and must be returned when requested – that’s not actually the case.
The actual true distinction is that:
- “Direct Memory” is memory allocated under the traditional video game model, so the game controls all aspects of its allocation
- “Flexible Memory” is memory managed by the PS4 OS on the game’s behalf, and allows games to use some very nice FreeBSD virtual memory functionality. However this memory is 100 per cent the game’s memory, and is never used by the OS, and as it is the game’s memory it should be easy for every developer to use it.
We have no comment to make on the amount of memory reserved by the system or what it is used for.
By not commenting on the amount of RAM reserved by the system or available to developers, Sony might implicitly confirm the previous figures.
Eurogamer, originally reporting on the PS4′s memory, now thinks that there is 4.5GB of Direct RAM available to developers, along with OS-controlled 1GB of memory, therefore the amount of memory the games will have 100% access would be 5.5GB leaving 2.5GB reserved for the OS.
We understand that this is a 1GB virtual address space, split into two areas – 512MB of on-chip RAM is used (the physical area) and another 512MB is “paged”, perhaps like a Windows swap file. But to be clear, of the 8GB of GDDR5 on PS4, our contention is that 5GB of it is available to developers.
The good news is that the amount is static and not dictated by OS functions as we stated in our original post, making it a lot easier for developers to work with.