# Re: \[PATCH\] swiotlb: set IO TLB segment size via cmdline

- From: Jan Beulich \<hidden\>
- Date: 2021-09-17 09:52:26 
- List: linux-doc
- Page: https://ratatoskr.run/linux-doc/2021/09/1512751
- Thread: https://ratatoskr.run/xen-devel/2021/09/1508104/t.md

```text
On 17.09.2021 11:36, Roman Skakun wrote:
> I use Xen PV display. In my case, PV display backend(Dom0) allocates
> contiguous buffer via DMA-API to
> to implement zero-copy between Dom0 and DomU.

Why does the buffer need to be allocated by Dom0? If it was allocated
by DomU, it could use grants to give the backend direct (zero-copy)
access.

Jan

```