Re: [Qemu-devel] [PATCH v2 3/3] xen-hvm: try to use xenforeignmemory_map_resource() to map ioreq pages

[Anthony PERARD]

On Tue, May 15, 2018 at 04:45:25PM +0100, Paul Durrant wrote:
> > > diff --git a/include/hw/xen/xen_common.h
> > b/include/hw/xen/xen_common.h
> > > index 5f1402b494..d925751040 100644
> > > --- a/include/hw/xen/xen_common.h
> > > +++ b/include/hw/xen/xen_common.h
> > > @@ -119,6 +119,20 @@ static inline int
> > xendevicemodel_pin_memory_cacheattr(
> > >      return xc_domain_pin_memory_cacheattr(xen_xc, domid, start, end,
> > type);
> > >  }
> > >
> > > +typedef void xenforeignmemory_resource_handle;
> > > +
> > > +#define XENMEM_resource_ioreq_server_frame_bufioreq 0
> > > +#define XENMEM_resource_ioreq_server_frame_ioreq(n) (1 + (n))
> > > +
> > > +static inline xenforeignmemory_resource_handle
> > *xenforeignmemory_map_resource(
> > > +    xenforeignmemory_handle *fmem, domid_t domid, unsigned int type,
> > > +    unsigned int id, unsigned long frame, unsigned long nr_frames,
> > > +    void **paddr, int prot, int flags)
> > > +{
> > > +    errno = EOPNOTSUPP;
> > 
> > I think ENOSYS would be better. EOPNOTSUPP seems to be for sockets.
> > 
> 
> No, EOPNOTSUPP is more general than that and is convention for unimplemented 
> API operations elsewhere. ENOSYS is supposed to strictly mean 'system call 
> not implemented' but we use it for hypercalls in Xen, leading to occasional 
> fun with Linux checkpatch.pl.

In man errno, I have:
ENOTSUP         Operation not supported (POSIX.1-2001)
EOPNOTSUPP      Operation not supported on socket (POSIX.1-2001).
ENOSYS          Function not implemented (POSIX.1-2001).

But I guess any of these would work.

-- 
Anthony PERARD