It is related to the fact that you are not using the Linux SMP kernel, therefore, the APIC (Advanced Programmable Interrupt Controller) who provides up to 255 IRQs is not in use. This can be caused by:

1. when you boot from Linux, you have chosen normal kernel, there is also a SMP kernel option.

2. You use single Xeon processor (SMP supports only dual processing). If you are using single processor, please enable Hyper-threading in the BIOS. The BIOS and OS will see two CPUs and the SMP kernel option when you boot into Linux will show up. Now you can check /proc/interrupts and see the APIC is used