Visible to Intel only — GUID: lro1403291970950
Ixiasoft
Visible to Intel only — GUID: lro1403291970950
Ixiasoft
54.1. Core Overview
In the PCI subsystem, Message Signaled Interrupts (MSI) is a feature that enables a device function to request service by writing a system-specified data value to a system-specified message address (using a PCI DWORD memory write transaction). System software initializes the message address and message data during device configuration, allocating one or more system-specified data and system-specified message addresses to each MSI capable function.
A MSI target (receiver), Intel FPGA PCIe RootPort Hard IP, receives MSI interrupts through the Avalon® Streaming ( Avalon® -ST) RX TLP of type MWr. For Avalon® -MM based PCIe RootPort Hard IP, the RP_Master issues a write transaction with the system-specified message data value to the system-specified message address of a MSI TLP received. This memory mapped mechanism does not issue any interrupt output to host the processor; and it relies on the host processor to poll the value changes at the system-specified message address in order to acknowledge the interrupt request and service the MSI interrupt. This polling mechanism may overwhelm the processor cycles and it is not efficient.
The Intel FPGA MSI-to-GIC Generator is introduced with the purpose of allowing level interrupt generation to the host processor upon arrival of a MSI interrupt. It exists as a separate module to Intel FPGA PCIe HIP for completing the interrupt generation to host the processor upon arrival of a MSI TLP.