PCI MSI Msi-x Learning Notes

MSI appears in PCI2.2, and PCI 3.0 allows masks to be set for each interrupt

Msi-x appears in PCI3.0, relative to MSI, each device allows more interrupts, each interrupt can be configured independently

Basic functions

The device throws an interrupt by writing to a specific address

Compared to traditional pin-based PCI interrupts:

1. Traditional PCI interrupts need to be shared between devices, MSI Msi-x does not need to be shared

2. Traditional PCI interrupts cause interrupts before the device writes data to memory, which must be handled by the interrupt handler, which requires polling a register of the device to determine that the data is in place, which is more likely to occur in the Pci-pci Bridge extended PCI bus

MSI Mis-x does not occur when the interrupt is raised to ensure that the data is in place

3. Traditional PCI interrupts, one device supports only one interrupt, and drivers often need to use the device to determine the specific event that is raised, MSI msi-x a device to support multiple interrupts