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deviantbit | 11 months ago

Unified memory doesn't mean unified address space. It frustrates me when no one understands unified memory.

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morphle|11 months ago

If you fix the pages tables (partial tutorial online) you can have continuous unified address space on Apple Silicon.

deviantbit|11 months ago

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.