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Re: Silence compiler warning in arch/x86/kvm/emulate.c

From Paolo Bonzini <pbonzini@redhat.com>
Newsgroups linux.kernel
Subject Re: Silence compiler warning in arch/x86/kvm/emulate.c
Date 2016-02-19 19:00 +0100
Message-ID <r3Xvs-qi-3@gated-at.bofh.it> (permalink)
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On 19/02/2016 18:54, Valdis.Kletnieks@vt.edu wrote:
> la can get changed here - but there's 2 cases to consider.  If it's
> in a 32-bit kernel, anding with -1 is a no-op.
> 
> Now if we're on a 64-bit kernel, the 'and' clears the high 32
> bits.
> 
> But under what conditions is 'la' a 64-bit quantity that has any
> bits set in the high 32 bits (meaning it's a pointer to something 
> over the 4G line) - but it's still valid to smash those bits?

That can happen for example if there is a non-zero segment base.  Then
the linear address wraps at 4G.

Paolo
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Thread

Re: Silence compiler warning in  arch/x86/kvm/emulate.c Aurelien Jarno <aurelien@aurel32.net> - 2016-02-19 13:00 +0100
  Re: Silence compiler warning in arch/x86/kvm/emulate.c Paolo Bonzini <pbonzini@redhat.com> - 2016-02-19 13:10 +0100
    Re: Silence compiler warning in arch/x86/kvm/emulate.c Aurelien Jarno <aurelien@aurel32.net> - 2016-02-19 18:10 +0100
  Re: Silence compiler warning in  arch/x86/kvm/emulate.c Aurelien Jarno <aurelien@aurel32.net> - 2016-02-19 17:50 +0100
    Re: Silence compiler warning in arch/x86/kvm/emulate.c Valdis.Kletnieks@vt.edu - 2016-02-19 19:00 +0100
      Re: Silence compiler warning in arch/x86/kvm/emulate.c Paolo Bonzini <pbonzini@redhat.com> - 2016-02-19 19:00 +0100
        Re: Silence compiler warning in arch/x86/kvm/emulate.c Valdis.Kletnieks@vt.edu - 2016-02-20 01:40 +0100

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