Re: [PATCH 3/3] x86/irq: update first_system_vector only when X86_LOCAL_PIC is on

From: Thomas Gleixner
Date: Sun Mar 13 2016 - 05:13:52 EST

On Sun, 13 Mar 2016, Jianyu Zhan wrote:
> On Sun, Mar 13, 2016 at 3:55 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> > if LOCAL_APIC is disabled it does not use the interrupt, simply because there
> > is no way to trigger it. That setup is inside #ifdef CONFIG_X86_LOCAL_APIC for
> > exactly that reason.
> >
> > Just because IRQ_WORK has no config dependency on LOCAL APIC that does not
> > mean it uses the interrupt gate unconditionally.
> >
> Thanks for clarification.
> I think IRQ_WORK works as generic hardirq context callbacks, it should reply on
> self IPI, which is a functionality provided by LOCAL_APIC, while
> legacy PIC doesn't
> provide this(correct?).

As I said before IRQ_WORK can work w/o APIC. And therefor IRQ_WORK does NOT
depend on APIC.

End of story. Nothing to change here at all.