[PATCH] net/af_xdp: make compatible with libbpf v0.8.0

[Loftus, Ciara]

> 
> On 6/24/22 13:23, Ciara Loftus wrote:
> > libbpf v0.8.0 deprecates the bpf_get_link_xdp_id and bpf_set_link_xdp_fd
> > functions. Use meson to detect if libbpf >= v0.7.0 is linked and if so, use
> > the recommended replacement functions bpf_xdp_query_id,
> bpf_xdp_attach
> > and bpf_xdp_detach which are available to use since libbpf v0.7.0.
> >
> > Also prevent linking with libbpf versions > v0.8.0.
> >
> > Signed-off-by: Ciara Loftus <ciara.loftus at intel.com>
> > ---
> >   doc/guides/nics/af_xdp.rst          |  3 ++-
> >   drivers/net/af_xdp/compat.h         | 36
> ++++++++++++++++++++++++++++-
> >   drivers/net/af_xdp/meson.build      |  7 ++----
> >   drivers/net/af_xdp/rte_eth_af_xdp.c | 19 +++------------
> >   4 files changed, 42 insertions(+), 23 deletions(-)
> 
> Don't we need to mention these changes in release notes?
> 
> >
> > diff --git a/doc/guides/nics/af_xdp.rst b/doc/guides/nics/af_xdp.rst
> > index 56681c8365..9edb48df67 100644
> > --- a/doc/guides/nics/af_xdp.rst
> > +++ b/doc/guides/nics/af_xdp.rst
> > @@ -43,7 +43,8 @@ Prerequisites
> >   This is a Linux-specific PMD, thus the following prerequisites apply:
> >
> >   *  A Linux Kernel (version > v4.18) with XDP sockets configuration enabled;
> > -*  Both libxdp >=v1.2.2 and libbpf libraries installed, or, libbpf <=v0.6.0
> > +*  Both libxdp >=v1.2.2 and libbpf <=v0.8.0 libraries installed, or, libbpf
> > +   <=v0.6.0.
> >   *  If using libxdp, it requires an environment variable called
> >      LIBXDP_OBJECT_PATH to be set to the location of where libxdp placed its
> bpf
> >      object files. This is usually in /usr/local/lib/bpf or /usr/local/lib64/bpf.
> > diff --git a/drivers/net/af_xdp/compat.h b/drivers/net/af_xdp/compat.h
> > index 28ea64aeaa..8f4ac8b5ea 100644
> > --- a/drivers/net/af_xdp/compat.h
> > +++ b/drivers/net/af_xdp/compat.h
> > @@ -60,7 +60,7 @@ tx_syscall_needed(struct xsk_ring_prod *q
> __rte_unused)
> >   }
> >   #endif
> >
> > -#ifdef RTE_NET_AF_XDP_LIBBPF_OBJ_OPEN
> > +#ifdef RTE_NET_AF_XDP_LIBBPF_V070
> 
> Typically version-based checks are considered as bad. Isn't it
> better use feature-based checks/defines?

Hi Andrew,

Thank you for the feedback. Is the feature-based checking something that we can push to the next release?

We are already using the pkg-config version-check method for other libraries/features in the meson.build file:
* libxdp >= v1.2.2 # earliest compatible libxdp release
* libbpf >= v0.7.0 # bpf_object__* functions
* libbpf >= v0.2.0 # shared umem feature

If we change to your suggested method I think we should change them all in one patch. IMO it's probably too close to the release to change them all right now. What do you think?

Thanks,
Ciara