Subject: RE: [PATCH v4 bpf-next 07/10] selftests: xsk: introduce default Rx pkt stream

From: John Fastabend <[email-masked]>
Date: Fri, 17 Jun 2022 19:41:19 -0700

Maciej Fijalkowski wrote:
> In order to prepare xdpxceiver for physical device testing, let us
> introduce default Rx pkt stream. Reason for doing it is that physical
> device testing will use a UMEM with a doubled size where half of it will
> be used by Tx and other half by Rx. This means that pkt addresses will
> differ for Tx and Rx streams. Rx thread will initialize the
> xsk_umem_info::base_addr that is added here so that pkt_set(), when
> working on Rx UMEM will add this offset and second half of UMEM space
> will be used. Note that currently base_addr is 0 on both sides. Future
> commit will do the mentioned initialization.
> 
> Previously, veth based testing worked on separate UMEMs, so single
> default stream was fine.
> 
> Acked-by: Magnus Karlsson <[email-masked]>
> Signed-off-by: Maciej Fijalkowski <[email-masked]>
> ---

Just curious why can't we make veth use a single umem with double size?
Would be nice to have a single test setup. Why choose two vs a single
size.

Thanks.