Re: [PATCH v6 1/6] arm/arm64: add smccc

Will Deacon
2015-11-02T14:45:29Z

On Mon, Nov 02, 2015 at 02:03:13PM +0000, Mark Rutland wrote:
> > > > +/**
> > > > + * struct smccc_res - Result from SMC/HVC call
> > > > + * @a0-a3 result values from registers 0 to 3
> > > > + */
> > > > +struct smccc_res {
> > > > + unsigned long a0;
> > > > + unsigned long a1;
> > > > + unsigned long a2;
> > > > + unsigned long a3;
> > > > +};
> > >
> > > Are there any endianness considerations for this structure?
> >
> > No, I can't find anything in the ARM SMC Calling Convention document
> > indicating that.
>
> The calling conventions have no bearing on the structure, which is our
> invention.
>
> We stash register values (which don't have endianness) returned by the
> firmeware into the structure in the sequences above (which appear
> endian-clean to me).

Ah yes, the structure is populated by the kernel not the firmware, so
there's nothing to worry about. Thanks for the explanation.

Will