Re: [PATCH net-next v4] ppp: enable TX scatter-gather

Qingfang Deng
2026-02-03T15:08:41Z

On Tue, Feb 3, 2026 at 6:55 PM Paolo Abeni <pabeni@redhat.com> wrote:
> I'm sorry for missing this point before, but AFAICS channels with
> chan->direct_xmit == 0 do not support GSO packets at all, and here such
> packets will be transmitted after linearization (but still as GSO).
>
> I think that while transmitting over !chan->direct_xmit you additionally
> need to check for GSO packet. If ppp features are recomputed depending
> on the channels configuration, you could chose to drop such packets.
> Otherwise you will need to segment them before transmission, and that
> looks error prone in case of multilink.

I don't think that's true. Using the current features set (NETIF_F_SG
| NETIF_F_FRAGLIST), the network core will only enable the generic
software GSO (NETIF_F_GSO), and a GSO skb will be segmented in
validate_xmit_skb before being passed to the PPP driver.

>
> /P