PCIe, BAR0, and DMA Explained with QEMU
Published at September 24, 2025 · 7 min read
Introduction In this post, we’ll break down how BAR0 and DMA interact in PCIe devices. This is the theoretical foundation of a two-part series: Part 1 (this post): BARs, DMA flows, and system-level design. Part 2 (next post): Full hands-on implementation with QEMU and a Linux kernel driver. 💡 Historical note: In old ISA systems, the CPU directly drove parallel address + data lines to the card. With PCIe, the same principle applies — the CPU still writes to registers —...