linux-kernel - Re: [PATCH v3] enable x2APIC without interrupt remapping under KVM

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Message-ID: <20090629154552.GB8122@redhat.com>
Date:	Mon, 29 Jun 2009 18:45:52 +0300
From:	Gleb Natapov <gleb@...hat.com>
To:	Suresh Siddha <suresh.b.siddha@...el.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Sheng Yang <sheng@...ux.intel.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"avi@...hat.com" <avi@...hat.com>
Subject: Re: [PATCH v3] enable x2APIC without interrupt remapping under KVM

On Mon, Jun 29, 2009 at 08:15:05AM -0700, Suresh Siddha wrote:
> On Mon, 2009-06-29 at 08:10 -0700, Gleb Natapov wrote:
> > On Mon, Jun 29, 2009 at 07:58:39AM -0700, Suresh Siddha wrote:
> > > Thinking more, probably we shouldn't remove this dependency. This might
> > > encourage people (knowingly or unknowingly) to enable x2apic without
> > > interrupt-remapping. Can we remove this? KVM mode will still work even
> > > if we fail to enable interrupt-remapping. So this shouldn't be an issue,
> > > correct?
> > > 
> > Yes, KVM will still work. I don't have strong fillings one way or the
> > other, but why mandate an option that is no longer mandatory. What
> > others think?
> 
> Only under the presence of KVM we are breaking this dependency. And
> typically the same kernel runs natively and under the presence of kvm
> correct. So thats why we shouldn't break this dependency.
> 
OK, I'll drop Kconfig part in the next version. Unless someone will
object till tomorrow. 

> 
> > > >  	ioapic_entries = alloc_ioapic_entries();
> > > >  	if (!ioapic_entries) {
> > > > -		pr_info("Allocate ioapic_entries failed: %d\n", ret);
> > > > -		goto end;
> > > > +		 pr_info("Allocate ioapic_entries failed\n");
> > > > +		 return;
> > > 
> > > 
> > > We should go to ir_failed ..
> > Why? There is not more ir_failed.
> 
> oops. Not literally. We should goto the point where we should report the
> x2apic or ir enabling failed and check for x2apic pre-enabled etc at the
> end.
> 
Ah, OK.

--
			Gleb.
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