Re: [Xen-devel] [PATCH v2 2/2] swiotlb-xen: implement xen_swiotlb_get_sgtable callback

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 18 Jan 2017, Andrii Anisov wrote:
> Stefano,
> 
> About this piece:
> 
> >
> > -       if (__generic_dma_ops(dev)->get_sgtable)
> > +
> > +       if (__generic_dma_ops(dev)->get_sgtable) {
> > +               /* We can't handle foreign pages here. */
> > +#ifdef CONFIG_ARM
> > +               unsigned long bfn = dma_to_pfn(dev, handle);
> > +#else
> > +               unsigned long bfn = handle >> PAGE_SHIFT;
> > +#endif
> > +               BUG_ON (!page_is_ram(bfn));
> >                 return __generic_dma_ops(dev)->get_sgtable(dev, sgt, 
> > cpu_addr, handle,
> >                                                                  size, 
> > attrs);
> > +       }
> >         return dma_common_get_sgtable(dev, sgt, cpu_addr, handle, size);
> >  }
> 
> 
> Would it be in drivers/xen/swiotlb-xen.c as you suggested, the whole
> "if (__generic_dma_ops(dev)->get_sgtable) {}" should be under ifdef.
> 
> IMO it would be better to avoid ifdefs in drivers/xen/swiotlb-xen.c,
> but I haven't find out how to do that.

Yes, I dislike ifdef like everybody else, but sometimes they are
unavoidable.

But please test this code because I only compile tested it :-)

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