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From: Ian Campbell <ijc@hellion.org.uk>
To: Sheng Yang <sheng@linux.intel.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@elte.hu>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2 v2] xen: HVM X2APIC support
Date: Wed, 05 Jan 2011 14:56:28 +0000	[thread overview]
Message-ID: <1294239388.3831.3516.camel@zakaz.uk.xensource.com> (raw)
In-Reply-To: <201101051547.12107.sheng@linux.intel.com>

> > @@ -1384,6 +1365,17 @@ static bool __init xen_hvm_platform(void)
> >       return true;
> >  }
> > 
> > +bool xen_hvm_need_lapic(void)
> > +{
> > +     if (xen_pv_domain())
> > +             return false;
> > +     if (xen_hvm_domain() && xen_feature(XENFEAT_hvm_pirqs) &&
> > +                     xen_have_vector_callback)
> > +             return false;
> > +     return (xen_cpuid_base() != 0);
> > +}
> > +EXPORT_SYMBOL_GPL(xen_hvm_need_lapic);
> > +

Since xen_hvm_domain() is always true if xen_cpuid_base() != 0, isn't
this more obviously written as:
	if (!xen_hvm_domain())
		return false;
	if (xen_feature(XENFEAT_hvm_pirqs) && xen_have_vector_callback)
		return false;
	return true;
?

Also, checking for the XenVMMXenVMM signature alone seems like a very
broad test for checking the availability of a specific feature, is there
nothing more specific which we could/should be testing?

Ian.

-- 
Ian Campbell
Current Noise: Taint - Mass Appeal Sadness

What's a cult?  It just means not enough people to make a minority.
		-- Robert Altman


  reply	other threads:[~2011-01-05 15:10 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-21  6:18 [PATCH 1/2] apic: Move hypervisor detection of x2apic to hypervisor.h Sheng Yang
2010-12-21  6:18 ` [PATCH 2/2 v2] xen: HVM X2APIC support Sheng Yang
2011-01-05  7:47   ` Sheng Yang
2011-01-05 14:56     ` Ian Campbell [this message]
2011-01-06  1:20       ` Sheng Yang
2011-01-06  9:10         ` Ian Campbell
2011-01-06  9:23           ` Sheng Yang
2011-01-06  9:35             ` Ian Campbell
2011-01-06 10:05               ` Sheng Yang
2011-01-06 15:00                 ` Konrad Rzeszutek Wilk
2011-01-10  2:34                   ` Sheng Yang
2010-12-21 17:15 ` [PATCH 1/2] apic: Move hypervisor detection of x2apic to hypervisor.h Jeremy Fitzhardinge
2010-12-21 18:15   ` Avi Kivity
2010-12-31  2:05     ` Sheng Yang
2011-01-04  8:57     ` Sheng Yang
2011-01-04  9:24       ` Ingo Molnar
2011-01-05  1:51         ` Sheng Yang
2011-01-05  7:40           ` Jeremy Fitzhardinge
2011-01-05 15:46             ` Konrad Rzeszutek Wilk
  -- strict thread matches above, loose matches on Subject: below --
2010-12-08  6:03 Sheng Yang
2010-12-08  6:04 ` [PATCH 2/2 v2] xen: HVM X2APIC support Sheng Yang
2010-12-17  8:20   ` Sheng Yang

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