FreeBSD Device Drivers

MSI Management Routines

The FreeBSD kernel provides the following functions for working with MSI:

#include <dev/pci/pcivar.h>

int
pci_msix_count(device_t dev);

int
pci_msi_count(device_t dev);

int
pci_alloc_msix(device_t dev, int *count);

int
pci_alloc_msi(device_t dev, int *count);

int
pci_release_msi(device_t dev);

The pci_msix_count and pci_msi_count functions return the number of unique MSI-X or MSI messages maintained by the device dev.

The pci_alloc_msix and pci_alloc_msi functions allocate count MSI-X or MSI vectors based on dev. If there are not enough free vectors, fewer than count vectors will be allocated. Upon a successful return, count will contain the number of vectors allocated. (MSI-X and MSI vectors were described in Implementing ...