2 ms·
> were given an address that they can mmap for direct reads/writes from/to the peripherals address space Kernel-mode drivers indeed do that under the hood, but
by Const-me 6y ago
> were given an address that they can mmap for direct reads/writes from/to the peripherals address space
Kernel-mode drivers indeed do that under the hood, but the majority of GPU I/O bandwidth doesn’t go that way.
With DMA, GPUs have full access to system memory. They have specialized piece of hardware (exposed to programmers as copy command queue in D3D12, or transfer queue in Vulcan) to move large blocks of data in either direction between system RAM and VRAM.