Return the number of msi vectors a device can send
int pci_msi_vec_count(struct pci_dev * dev);
dev
device to report about
This function returns the number of MSI vectors a device requested via Multiple Message Capable register. It returns a negative errno if the device is not capable sending MSI interrupts. Otherwise, the call succeeds and returns a power of two, up to a maximum of 2^5 (32), according to the MSI specification.