To prevent another incidental removal of the IRQ2 ignore logic in the IO/APIC code going unnoticed add a sanity check. Add some commentry at the other place which ignores IRQ2 while at it.
Signed-off-by: Thomas Gleixner <[email protected]> --- arch/x86/kernel/apic/vector.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) --- a/arch/x86/kernel/apic/vector.c +++ b/arch/x86/kernel/apic/vector.c @@ -543,6 +543,14 @@ static int x86_vector_alloc_irqs(struct if ((info->flags & X86_IRQ_ALLOC_CONTIGUOUS_VECTORS) && nr_irqs > 1) return -ENOSYS; + /* + * Catch any attempt to touch the cascade interrupt on a PIC + * equipped system. + */ + if (WARN_ON_ONCE(info->flags & X86_IRQ_ALLOC_LEGACY && + virq == PIC_CASCADE_IR)) + return -EINVAL; + for (i = 0; i < nr_irqs; i++) { irqd = irq_domain_get_irq_data(domain, virq + i); BUG_ON(!irqd); @@ -745,6 +753,11 @@ void __init lapic_assign_system_vectors( /* Mark the preallocated legacy interrupts */ for (i = 0; i < nr_legacy_irqs(); i++) { + /* + * Don't touch the cascade interrupt. It's unusable + * on PIC equipped machines. See the large comment + * in the IO/APIC code. + */ if (i != PIC_CASCADE_IR) irq_matrix_assign(vector_matrix, ISA_IRQ_VECTOR(i)); }
