Messages in this thread | | | Date | Sun, 20 Sep 2009 22:30:11 +0400 | From | Cyrill Gorcunov <> | Subject | Re: [PATCH] x86: Don't ack_APIC_irq() if lapic is disabled in GENERIC_INTERRUPT_VECTOR handler |
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[Ingo Molnar - Sun, Sep 20, 2009 at 08:21:24PM +0200] | | * Cyrill Gorcunov <gorcunov@gmail.com> wrote: | | > [Ingo Molnar - Sun, Sep 20, 2009 at 08:06:32PM +0200] | > | | > | * Sheng Yang <sheng@linux.intel.com> wrote: | > | | > | > Otherwise would cause trouble... | > | > | > | > Cc: Dimitri Sivanich <sivanich@sgi.com> | > | > Signed-off-by: Sheng Yang <sheng@linux.intel.com> | > | > --- | > | > arch/x86/kernel/irq.c | 3 ++- | > | > 1 files changed, 2 insertions(+), 1 deletions(-) | > | > | > | > diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c | > | > index b0cdde6..78b23d0 100644 | > | > --- a/arch/x86/kernel/irq.c | > | > +++ b/arch/x86/kernel/irq.c | > | > @@ -257,7 +257,8 @@ void smp_generic_interrupt(struct pt_regs *regs) | > | > { | > | > struct pt_regs *old_regs = set_irq_regs(regs); | > | > | > | > - ack_APIC_irq(); | > | > + if (!disable_apic) | > | > + ack_APIC_irq(); | > | | > | Wont in that case the apic->ack method be a NOP? | > | | > | Ingo | > | | > | > iirc it was Xen related patch. So it's not that simple. | > | > I've pointed out Sheng about disable_apic. I'm not Xen | > specialist but Xen team seem to use specific apic setup | > so our "dummy" operations are not involved (case they | > set disable_apic=1 without "turn off" apic ops in real). | > Something like that. | | They should then set a NOP function in that case. We really dont want to | slow down hotpath functions like smp_generic_interrupt() with flaggery. | | Ingo |
Well, I suppose we should wait for Sheng's comments. I wish I would answer you but I simply don't know Xen code :)
-- Cyrill
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