msi - Message Signaled Interrupt
Messaged Signaled Interrupts are used in modern PCI as well as some ARM GIC controllers. MSI objects allow a privileged userspace process to allocate a range of MSIs and associated IRQ vectors for use with device drivers to allocate
The most common use for an MSI object is to allocate a range of MSIs to provide to a PCI device's Message Signaled Interrupt Capability. Subsequently, the platform or PCI bus driver may use this object to allocate
interrupt objects corresponding to those MSIs for use in downstream device drivers.