Re: DMA error when sg->offset value is greater than PAGE_SIZE in Intel IOMMU

[David Woodhouse]

On Wed, 2017-09-20 at 16:01 +0800, Herbert Xu wrote:
> Harsh Jain <Harsh@xxxxxxxxxxx> wrote:
> >Â
> > While debugging DMA mapping error in chelsio crypto driver we
> observed that when scatter/gather list received by driver has some
> entry with page->offset > 4096 (PAGE_SIZE). It starts giving DMA
> error. Without IOMMU it works fine.
> 
> This is not a bug. The network stack can and will feed us such
> SG lists.

Hm? Under what circumstances is the offset permitted to be >
PAGE_SIZE?Â

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