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Re: [Xen-devel][PATCH 3/5] Add cpufreq pwr mgmt to Xen


  • To: "Liu, Jinsong" <jinsong.liu@xxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
  • Date: Tue, 13 May 2008 10:44:20 +0100
  • Delivery-date: Tue, 13 May 2008 02:44:57 -0700
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: Aci0pum5DchKJJryTjCAyBnEoEeG2AAMDsoTAAEUb1AAAJ0Lyg==
  • Thread-topic: [Xen-devel][PATCH 3/5] Add cpufreq pwr mgmt to Xen

On 13/5/08 10:34, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx> wrote:

> I add a local variable 'a' in common/domain.c, since need to do '
> xen_processor_pmbits &= (~a);'
> If we directly use ' xen_processor_pmbits &= (~XEN_PROCESSOR_PM_PX)' may
> result in some align issue if xen_processor_pmbits is not 32bits
> variable.
> So I add 'a' with same type as 'xen_processor_pmbits'.

If this is a concern then cast XEN_PROCESSOR_PM_PX before applying ~.
Actually the right thing will happen without that since XEN_PROCESSOR_PM_PX
is a signed constant, so when the bitwise-negated value is widened it will
be sign extended.

 -- Keir



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