Subject: Re: [PATCH v4 bpf-next 15/22] xsk: add multi-buffer documentation

From: Maciej Fijalkowski <[email-masked]>
Date: Thu, 29 Jun 2023 22:28:49 +0200

On Wed, Jun 28, 2023 at 11:02:06PM +0200, Toke Høiland-Jørgensen wrote:
> > diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
> > index a4270fafdf11..b24244f768e3 100644
> > --- a/net/core/netdev-genl.c
> > +++ b/net/core/netdev-genl.c
> > @@ -19,6 +19,8 @@ netdev_nl_dev_fill(struct net_device *netdev, struct sk_buff *rsp,
> >  		return -EMSGSIZE;
> >  
> >  	if (nla_put_u32(rsp, NETDEV_A_DEV_IFINDEX, netdev->ifindex) ||
> > +	    nla_put_u32(rsp, NETDEV_A_DEV_XDP_ZC_MAX_SEGS,
> > +			netdev->xdp_zc_max_segs) ||
> 
> Should this be omitted if the driver doesn't support zero-copy at all?

This is now set independently when allocing net_device struct, so this can
be read without issues. Furthermore this value should not be used to find
out if underlying driver supports ZC or not - let us keep using
xdp_features for that.

Does it make sense?

> -Toke