From: Alexei Starovoitov <alexei.starovoi...@gmail.com> Date: Wed, 7 Dec 2016 08:37:58 -0800
> On Wed, Dec 07, 2016 at 11:41:12AM +0000, Jakub Kicinski wrote: >> > I see nothing wrong if this is exposed/made visible in the usual way >> > through >> > ethtool -k as well. I guess at least that would be the expected way to >> > query >> > for such driver capabilities. >> >> +1 on exposing this to user space. Whether via ethtool -k or a >> separate XDP-specific netlink message is mostly a question of whether >> we expect the need to expose more complex capabilities than bits. > > I'm very much against using NETIF_F_ flags and exposing this to user space. > I see this xdp feature flag as temporary workaround until all drivers > support adjust_head() helper. It is very much a fundamental feature for xdp. > Without being able to add/remove headers the usability of xdp becomes very > limited. > > If you guys dont like extra ndo_xdp command, I'd suggest to do > "if (prog->xdp_adjust_head)" check in the driver and if driver doesn't > support it yet, just fail XDP_SETUP_PROG command. > imo that will be more flexible interface, since in the future drivers > can fail on different combination of features and simple boolean flag > unlikely to serve us for long time. Indeed, if the eventual plan is to have all drivers be required to support a fundamental set of XDP features then exporting this in any way to userspace is not a good idea.
