Re: [Xen-devel] [PATCH v2 4/5] xen/gnttab: Refactor gnttab_clear_flag() to be gnttab_clear_flags()

[Julien Grall <julien.grall@xxxxxxx>]

Hi,

On 7/8/19 7:11 PM, Andrew Cooper wrote:
> On 07/07/2019 19:42, Julien Grall wrote:
> > Hi Andrew,
> >
> > On 7/4/19 8:14 PM, Andrew Cooper wrote:
> > > To allow for further improvements, it is useful to be able to clear
> > > more than
> > > a single flag at once.  Rework gnttab_clear_flag() into
> > > gnttab_clear_flags()
> > > which takes a bitmask rather than a bit number.
> > >
> > > No practical change yet.
> > >
> > > Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> > > ---
> > > CC: Jan Beulich <JBeulich@xxxxxxxx>
> > > CC: Wei Liu <wl@xxxxxxx>
> > > CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> > > CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> > > CC: Julien Grall <julien.grall@xxxxxxx>
> > > CC: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> > >
> > > v2:
> > >    * Use unsigned int for the mask parameter
> > I don't seem to find the request on the ML. Technically the mask can
> > only be 16-bit. May I ask the reason of this change?
> It is on the mailing list, but an orphaned email due to Jan's email changes.
Is it the same problem as I have seen the past 6 months between Juergen 
and Jan's e-mail?
> https://lore.kernel.org/xen-devel/1561109798-8744-5-git-send-email-andrew.cooper3@xxxxxxxxxx/T/#t
To be honest, I think it is wrong to try to micro-optimize a common 
prototype for the benefit of one architecture and one compiler version 
(or even none per the e-mail).
One could also argue that this may be not beneficial for the non-x86 
architecture depending on how the compiler decide to do the cast from 
32-bit to 16-bit...
Cheers,

--
Julien Grall

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