Deepin Linux

Sep 23, 2026 · Fundamentals

Inside read(): How Data Moves from Disk to Memory via Kernel & DMA

This article dissects the Linux read() system call, revealing how user-space applications, the kernel, and hardware controllers collaborate via DMA to move data from disk into memory, covering parameters, return values, blocking modes, file-type differences, and the copy_to_user overhead versus mmap zero-copy.