Bridges and PCI Internal works
Introduction Have you ever thought how device memory mapping work internally? This article is going to explain peripheral devices internal since I've been asked couple of time to explain how peripheral devices works and are communicated with processors, for example, LPC controller, SCSI controller, LAN controller. Physical Memory partitioning by Host Bridge / NorthBridge As we all known, There's two way to communicate between processor to PCI devices(in PCI speaking master-slave) , I/O port access or Memory mapped access. For memory mapped access, for the same address, for example - 0xA1000, how hardware distinguish that's for devices, and isn't for system memory access? The secret is hidden by host bridge memory partitioning. In Host bridge / North Bridge, there's memory controller, and graphic controller and the root complex logic that connects to SouthBridge / PCH by Direct Media Interface (DMI) , to handle all device communication from processor. As f