Re: [PATCH net-next 2/3] net: page_pool: add the possibility to sync DMA memory for non-coherent devices

Ilias Apalodimas
2019-11-15T07:17:09Z

Hi Jonathan,

>
[...]
> > For the skb reserved queues, this depends on the 'anything'. If the rest
> > of the
> > layers touch (or rather write) into that area, then we'll again gave to
> > sync.
> > If we know that the data has not been altered though, we can hand them
> > back to
> > the device skipping that sync right?
>
> Sure, but this is also true for eBPF programs. How would the driver know
> that
> the data has not been altered / compacted by the upper layers?

I haven't looked that up in detail. I was just explaining the reasoning behind
picking a u8 instead of a flag. As Jesper pointed we can get the same result by
using len = 0, so i am fine with the proposed change.

Thanks
/Ilias
> --
> Jonathan