Re: [Xen-devel] [PATCH 2/2 v2] xen: arm: Set all bits in mfn_to_xen_entry()

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 21/08/2015 12:47, Chris (Christopher) Brand wrote:
> Hi Andrew,
>
> > On 21/08/15 00:33, Chris Brand wrote:
> > > Ensure that every bit has a specific value.
> > >
> > > Reported-by: Julien Grall <julien.grall@xxxxxxxxxx>
> > > Signed-off-by: Chris Brand <chris.brand@xxxxxxxxxxxx>
> > > ---
> > > v2 adds comments on pxn and avail.
> > This is no functional change, if the compiler is conforming to the C spec.
> >
> > The spec guarantees that structure initialisation like this causes unspecified
> > names to gain their default value.  As these are integer bitfields, the default
> > value is 0.
> >
> > What compiler is in use?  It would appear that it is buggy, or at least has
> > buggy scalar replacement optimisations.
> That's right. I'd forgotten about that. This was actually suggested by Julien in
> a review of another patch I sent. I haven't seen any problems this fixes.
I still think those patches are valid in order to know which value are 
set by default and what does it mean.
Regards,

--
Julien Grall

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