On Wed, Feb 17, 2021 at 3:26 AM Dan Siemon [off-list ref] wrote:

On Mon, 2021-02-15 at 22:38 +0100, Toke Høiland-Jørgensen wrote:

quoted

The idea is to keep libbpf focused on bpf, and move the AF_XDP stuff
to
libxdp (so the socket stuff in xsk.h). We're adding the existing code
wholesale, and keeping API compatibility during the move, so all
that's
needed is adding -lxdp when compiling. And obviously the existing
libbpf
code isn't going anywhere until such a time as there's a general
backwards compatibility-breaking deprecation in libbpf (which I
believe
Andrii is planning to do in an upcoming and as-of-yet unannounced
v1.0
release).

I maintain a Rust binding to the AF_XDP parts of libbpf [1][2]. On the
chance that more significant changes can be entertained in the switch
to libxdp... The fact that many required functions like the ring access
functions exist only in xsk.h makes building a binding more difficult
because we need to wrap it with an extra C function [3]. From that
perspective, it would be great if those could move to xsk.c.

The only reason they were put in xsk.h is performance. But with LTO
(link-time optimizations) being present in most C-compilers these
days, it might not be a valid argument anymore. I will perform some
experiments and let you know. As you say, it would be much nicer to
hide away these functions in the library proper and make your life
easier.

[1] - https://github.com/aterlo/afxdp-rs
[2] - https://github.com/alexforster/libbpf-sys
[3] - https://github.com/alexforster/libbpf-sys/blob/master/bindings.c