Re: [Xen-devel] [PATCH v6 06/18] vmx: Add some helper functions for Posted-Interrupts

["Wu, Feng" <feng.wu@xxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Monday, September 07, 2015 6:46 PM
> To: Wu, Feng
> Cc: Andrew Cooper; Tian, Kevin; xen-devel@xxxxxxxxxxxxx; Keir Fraser
> Subject: RE: [PATCH v6 06/18] vmx: Add some helper functions for
> Posted-Interrupts
> 
> >>> On 06.09.15 at 04:05, <feng.wu@xxxxxxxxx> wrote:
> 
> >
> >> -----Original Message-----
> >> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> >> Sent: Friday, September 04, 2015 10:40 PM
> >> To: Wu, Feng
> >> Cc: Andrew Cooper; Tian, Kevin; xen-devel@xxxxxxxxxxxxx; Keir Fraser
> >> Subject: Re: [PATCH v6 06/18] vmx: Add some helper functions for
> >> Posted-Interrupts
> >>
> >> >>> On 25.08.15 at 03:57, <feng.wu@xxxxxxxxx> wrote:
> >> > @@ -121,11 +122,31 @@ static inline int pi_test_and_clear_on(struct
> >> pi_desc *pi_desc)
> >> >      return test_and_clear_bit(POSTED_INTR_ON, &pi_desc->control);
> >> >  }
> >> >
> >> > +static inline int pi_test_on(struct pi_desc *pi_desc)
> >> > +{
> >> > +    return test_bit(POSTED_INTR_ON, &pi_desc->control);
> >> > +}
> >>
> >> For this and ...
> >>
> >> > +static inline int pi_test_sn(struct pi_desc *pi_desc)
> >> > +{
> >> > +    return test_bit(POSTED_INTR_SN, &pi_desc->control);
> >> > +}
> >>
> >> ... this I wonder whether using the bitfield you defined in the
> >> previous patch wouldn't allow the compiler more freedom in
> >> how to carry this out.
> >
> > I am sorry, I don't quite understand it. Do you mean: the bitfield
> > defined in previous patch is pointless, or using the bitfield here?
> 
> Use it here would seem preferable. (But please recall that I
> questioned this two fold access model - partly using bitfields,
> partly using bitops - earlier on, and ideally _all_ accesses to
> a certain kind of data structure would follow a single, uniform
> model.)

Yes, I remember your suggestion about this. So now I only use
bitops everywhere, in that case, do you think I still need to use
bitfields here?

Thanks,
Feng

> 
> Jan


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