On Tuesday 08 December 2015 17:23:40 Mauro Carvalho Chehab wrote:
> > > +
> > > +struct media_v2_topology {
> > > + __u32 topology_version;
> > > +
> > > + __u32 num_entities;
> > > + struct media_v2_entity *entities;
> >
> > The kernel seems to be moving to using __u64 instead of pointers in
> > userspace-
> > facing structures to avoid compat32 code.
>
> We had such discussion at the MC summit. I don't object to change to
> __u64, but we need to reach a consensus
>
Just saw the email fly by. Using a __u64 to pass a pointer is generally
the preferred method for most subsystems these days.
However, that means you probably want to extract the pointer from
that using something like
static inline void __user *get_upointer(u64 arg)
{
return (void __user *)(uintptr_t)arg;
}
This is the only way that I know that works on both 32-bit and 64-bit
architectures as well as the oddball s390 compat mode (which you don't
care about because there are no media devices on s390).
Arnd
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