dev
nvec
Allocate IRQs for a device with the MSI capability. This function returns a negative errno if an error occurs. If it is unable to allocate the number of interrupts requested, it returns the number of interrupts it might be able to allocate. If it successfully allocates at least the number of interrupts requested, it returns 0 and updates the dev's irq member to the lowest new interrupt number; the other interrupt numbers allocated to this device are consecutive.