On Thu, 1 Aug 2019 at 08:59, Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote:
>
> On Wed, Jul 31, 2019 at 8:21 AM Björn Töpel <bjorn.topel@xxxxxxxxx> wrote:
> >
> > On Tue, 30 Jul 2019 at 19:43, Kevin Laatz <kevin.laatz@xxxxxxxxx> wrote:
> > >
> > > This patch adds a 'flags' field to the umem_config and umem_reg structs.
> > > This will allow for more options to be added for configuring umems.
> > >
> > > The first use for the flags field is to add a flag for unaligned chunks
> > > mode. These flags can either be user-provided or filled with a default.
> > >
> > > Signed-off-by: Kevin Laatz <kevin.laatz@xxxxxxxxx>
> > > Signed-off-by: Ciara Loftus <ciara.loftus@xxxxxxxxx>
> > >
> > > ---
> > > v2:
> > > - Removed the headroom check from this patch. It has moved to the
> > > previous patch.
> > >
> > > v4:
> > > - modified chunk flag define
> > > ---
>
> [...]
>
> > > diff --git a/tools/lib/bpf/xsk.h b/tools/lib/bpf/xsk.h
> > > index 833a6e60d065..44a03d8c34b9 100644
> > > --- a/tools/lib/bpf/xsk.h
> > > +++ b/tools/lib/bpf/xsk.h
> > > @@ -170,12 +170,14 @@ LIBBPF_API int xsk_socket__fd(const struct xsk_socket *xsk);
> > > #define XSK_UMEM__DEFAULT_FRAME_SHIFT 12 /* 4096 bytes */
> > > #define XSK_UMEM__DEFAULT_FRAME_SIZE (1 << XSK_UMEM__DEFAULT_FRAME_SHIFT)
> > > #define XSK_UMEM__DEFAULT_FRAME_HEADROOM 0
> > > +#define XSK_UMEM__DEFAULT_FLAGS 0
> > >
> > > struct xsk_umem_config {
> > > __u32 fill_size;
> > > __u32 comp_size;
> > > __u32 frame_size;
> > > __u32 frame_headroom;
> > > + __u32 flags;
> >
> > And the flags addition here, unfortunately, requires symbol versioning
> > of xsk_umem__create(). That'll be the first in libbpf! :-)
>
> xsk_umem_config is passed by pointer to xsk_umem__create(), so this
> doesn't break ABI, does it?
>
Old application, dynamically linked to new libbpf.so will crash,
right? Old application passes old version of xsk_umem_config, and new
library accesses (non-existing) flag struct member.
Björn
> >
> >
> > Björn
> >
> > > };
> > >
> > > /* Flags for the libbpf_flags field. */
> > > --
> > > 2.17.1
> > >
> > > _______________________________________________
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> > > Intel-wired-lan@xxxxxxxxxx
> > > https://lists.osuosl.org/mailman/listinfo/intel-wired-lan
