What can I do if Xenomai and Linux devices share the same IRQ?
IRQ sharing between RT (Xenomai) and non-RT (Linux) domains is fragile – regardless of the CPU architecture, can easily destroy determinism on the RT side, and should therefore be avoided whenever possible. Sharing IRQs between RT devices is not problematic, but still comes with additional overhead compared to dedicated IRQ lines. The following approaches exist to untangle devices IRQ-wise: • If at least one of the devices is a PCI card, try to flip its position on the motherboard. • PC104+ cards sometimes have jumpers (yeah, they still exist) to change the IRQ line. Otherwise, their ordering in the PC104 stack also influences the IRQ line • Some (but not many) PC and notebook BIOSes allow to change the IRQ assignment. • Disable the conflicting Linux device (e.g. in the BIOS) or simply don’t load its driver. • Disable some other on-board device that is unneeded. Sometimes this helps to persuade the system to avoid shared IRQs. • Enable CONFIG_X86_LOCAL_APIC or CONFIG_X86_IO_APIC, it in
