13.1. Configuration over Protocol (CvP)
The Hard IP for PCI Express architecture has an option to configure the FPGA and initialize the PCI Express link. In prior devices, a single Program Object File (.pof) programmed the I/O ring and FPGA fabric before the PCIe link training and enumeration began. The .pof file is divided into two parts:
- The I/O bitstream contains the data to program the I/O ring, the Hard IP for PCI Express, and other elements that are considered part of the periphery image.
- The core bitstream contains the data to program the FPGA fabric.
When you select the CvP design flow, the I/O ring and PCI Express link are programmed first, allowing the PCI Express link to reach the L0 state and begin operation independently, before the rest of the core is programmed. After the PCI Express link is established, it can be used to program the rest of the device. The following figure shows the blocks that implement CvP.
CvP has the following advantages:
- Provides a simpler software model for configuration. A smart host can use the PCIe protocol and the application topology to initialize and update the FPGA fabric.
- Improves security for the proprietary core bitstream.
- Reduces system costs by reducing the size of the flash device to store the .pof.
- May reduce system size because a single CvP link can be used to configure multiple FPGAs.
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