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SubjectRe: [PATCH 09/11] swiotlb-xen: simplify cache maintainance
On Fri, Sep 06, 2019 at 10:19:01AM -0400, Boris Ostrovsky wrote:
> On 9/6/19 10:01 AM, Christoph Hellwig wrote:
> > On Fri, Sep 06, 2019 at 09:52:12AM -0400, Boris Ostrovsky wrote:
> >> We need nop definitions of these two for x86.
> >>
> >> Everything builds now but that's probably because the calls are under
> >> 'if (!dev_is_dma_coherent(dev))' which is always false so compiler
> >> optimized is out. I don't think we should rely on that.
> > That is how a lot of the kernel works. Provide protypes only for code
> > that is semantically compiled, but can't ever be called due to
> > IS_ENABLED() checks. It took me a while to get used to it, but it
> > actually is pretty nice as the linker does the work for you to check
> > that it really is never called. Much better than say a BUILD_BUG_ON().
> (with corrected Juergen's email)
> I know about IS_ENABLED() but I didn't realize that this is allowed for
> compile-time inlines and such as well.
> Anyway, for non-ARM bits
> Reviewed-by: Boris Ostrovsky <>

Acked-by: Konrad Rzeszutek Wilk <>

as well.

Albeit folks have tested this under x86 Xen with 'swiotlb=force' right?

I can test it myself but it will take a couple of days.
> If this goes via Xen tree then the first couple of patches need an ack
> from ARM maintainers.
> -boris

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