The PCI interrupt code in FreeBSD has been designed and implemented by several different people. Mike Smith and Warner Losh provided the initial support for PCI interrupt routing including support for using the $PIR routing table. Mike and Warner also conceived the idea of PCI busses asking their parent bridge driver to route interrupts. Mike also implemented the initial support for routing interrupts via the ACPI _PRT tables. Mitsuru Iwasaki and Nate Lawson implemented the first pci link management driver.
The work I have done on PCI interrupts was also greatly aided by others. Enhancements to the existing PCI routing code were sponsored by The Weather Channel, while the MSI code was sponsored by Yahoo!. Both companies sponsored my time and provided hardware for testing.
My biggest debt is owed to Mike Smith, however. Several years ago Mike sat down with me and explained exactly what the interrupt routing information in the MP Table meant and why the existing code in FreeBSD 4.x needed to be improved. He also encouraged me to work on ACPI and PCI interrupt routing general. On an even broader scale, Mike mentored me as a I transitioned from working on FreeBSD documentation to hacking on the source to the FreeBSD kernel including my work on SMP, ACPI, and PCI support.