Re: [PATCH v3 1/4] x86: PIT connects to pin 2 of IOAPIC

[Gleb Natapov <gleb@redhat.com>]

On Tue, Dec 04, 2012 at 05:32:31AM +0000, Zhang, Yang Z wrote:
> Gleb Natapov wrote on 2012-12-03:
> > On Mon, Dec 03, 2012 at 03:01:01PM +0800, Yang Zhang wrote:
> >> When PIT connects to IOAPIC, it route to pin 2 not pin 0.
> >> 
> > This hack didn't work for a long time and nobody complained. It
> > should be safe to get rid of it.
> This hack is used to work around an issue about RHEL4. Not sure whether anyone still uses RHEL4.
> 
Yes, I traced it back to 8c35f237, but the hack is broken for a long time
(~3 years?) and nobody complained. It is broken in rhel6 too and rhel4
is tested as a guest there, may be the problem was solved in rhel4. I
think we can remove it now. If problem re-appear, at least we will know
which guest exactly actually needs it.


> >> Signed-off-by: Yang Zhang <yang.z.zhang@intel.com>
> >> ---
> >>  virt/kvm/ioapic.c |    2 +-
> >>  1 files changed, 1 insertions(+), 1 deletions(-)
> >> diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c index
> >> cfb7e4d..166c450 100644 --- a/virt/kvm/ioapic.c +++ b/virt/kvm/ioapic.c
> >> @@ -181,7 +181,7 @@ static int ioapic_deliver(struct kvm_ioapic
> >> *ioapic, int irq)
> >> 
> >>  #ifdef CONFIG_X86
> >>  	/* Always delivery PIT interrupt to vcpu 0 */
> >> -	if (irq == 0) {
> >> +	if (irq == 2) {
> >>  		irqe.dest_mode = 0; /* Physical mode. */
> >>  		/* need to read apic_id from apic regiest since
> >>  		 * it can be rewritten */
> >> --
> >> 1.7.1
> > 
> > --
> > 			Gleb.
> 
> 
> Best regards,
> Yang
> 

--
			Gleb.