Comment by deviantbit
1 year ago
Unified memory doesn't mean unified address space. It frustrates me when no one understands unified memory.
1 year ago
Unified memory doesn't mean unified address space. It frustrates me when no one understands unified memory.
If you fix the pages tables (partial tutorial online) you can have continuous unified address space on Apple Silicon.
Let’s be honest, saying “just fix the page tables” is like telling someone they can fly if they “just rewrite gravity.”
Yes, on Apple Silicon, the hardware supports shared physical memory, and with enough “convincing”, you can rig up a contiguous virtual address space for both the CPU and GPU. Apple’s unified memory architecture makes that possible, but Apple’s APIs and memory managers don’t expose this easily or safely for a reason. You’re messing with MMU-level mappings on a tightly integrated system that treats memory as a first-class citizen of the security model.
I can tell you never programmed on an Amiga.
Oh yes I programmed all the Amiga models, mostly in assembly level. I reprogrammed the ROMs. I also published a magazine on all the Commodore computers internals and build lots of hardware for these machines.
We had the parallel Inmos Transputer systems during the heyday of the Amiga, they where much better designed than any the custom Amiga chips.
9 replies →
Not true. "just fix the page tables" took me 4 hours. And only 15 minutes with the Linux kernel on Apple Silicon.
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I know the APIs don't make it easy, that's precisely why I want different APIs.