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

["Chris (Christopher) Brand" <chris.brand@xxxxxxxxxxxx>]

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.

Chris


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel