On Thu, Nov 7, 2019 at 10:44 PM Song Liu <songliubraving@xxxxxx> wrote:
>
>
>
> > On Nov 7, 2019, at 8:20 PM, Andrii Nakryiko <andriin@xxxxxx> wrote:
> >
> > Add detection of BPF_F_MMAPABLE flag support for arrays and add it as an extra
> > flag to internal global data maps, if supported by kernel. This allows users
> > to memory-map global data and use it without BPF map operations, greatly
> > simplifying user experience.
> >
> > Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
>
> Acked-by: Song Liu <songliubraving@xxxxxx>
>
> With nit below.
>
> > ---
> > tools/lib/bpf/libbpf.c | 31 +++++++++++++++++++++++++++++--
> > 1 file changed, 29 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> > index fde6cb3e5d41..73607a31a068 100644
> > --- a/tools/lib/bpf/libbpf.c
> > +++ b/tools/lib/bpf/libbpf.c
> > @@ -142,6 +142,8 @@ struct bpf_capabilities {
> > __u32 btf_func:1;
> > /* BTF_KIND_VAR and BTF_KIND_DATASEC support */
> > __u32 btf_datasec:1;
> > + /* BPF_F_MMAPABLE is supported for arrays */
> > + __u32 array_mmap:1;
> > };
> >
> > /*
> > @@ -855,8 +857,6 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
> > pr_warn("failed to alloc map name\n");
> > return -ENOMEM;
> > }
> > - pr_debug("map '%s' (global data): at sec_idx %d, offset %zu.\n",
> > - map_name, map->sec_idx, map->sec_offset);
> >
> > def = &map->def;
> > def->type = BPF_MAP_TYPE_ARRAY;
> > @@ -864,6 +864,12 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
> > def->value_size = data->d_size;
> > def->max_entries = 1;
> > def->map_flags = type == LIBBPF_MAP_RODATA ? BPF_F_RDONLY_PROG : 0;
> > + if (obj->caps.array_mmap)
> > + def->map_flags |= BPF_F_MMAPABLE;
> > +
> > + pr_debug("map '%s' (global data): at sec_idx %d, offset %zu, flags %u.\n",
>
> nit: Better print flags as %x.
>
>
sure, will update
