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Date: Thu, 16 Feb 2017 17:09:30 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
        Chris Wright <chrisw@sous-sol.org>, Alok Kataria <akataria@vmware.com>,
        Rusty Russell <rusty@rustcorp.com.au>, Ingo Molnar <mingo@redhat.com>,
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        Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>,
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        Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Juergen Gross <jgross@suse.com>
Subject: Re: [PATCH v4 1/2] x86/paravirt: Change vcp_is_preempted() arg type
 to long
Message-ID: <20170216160930.GC6515@twins.programming.kicks-ass.net>
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On Wed, Feb 15, 2017 at 04:37:49PM -0500, Waiman Long wrote:
> The cpu argument in the function prototype of vcpu_is_preempted()
> is changed from int to long. That makes it easier to provide a better
> optimized assembly version of that function.
> 
> For Xen, vcpu_is_preempted(long) calls xen_vcpu_stolen(int), the
> downcast from long to int is not a problem as vCPU number won't exceed
> 32 bits.
> 

Note that because of the cast in PVOP_CALL_ARG1() this patch is
pointless.

Then again, it doesn't seem to affect code generation, so why not. Takes
away the reliance on that weird cast.