Re: [PATCH bpf-next] libbpf: Export bpf_object__load_vmlinux_btf

On Tue, May 26, 2020 at 7:09 PM Daniel Xu [off-list ref] wrote:

Right now the libbpf model encourages loading the entire object at once.
In this model, libbpf handles loading BTF from vmlinux for us. However,
it can be useful to selectively load certain maps and programs inside an
object without loading everything else.

There is no way to selectively load or not load a map. All maps are
created, unless they are reusing map FD or pinned instances. See
below, I'd like to understand the use case better.

In the latter model, there was perviously no way to load BTF on-demand.
This commit exports the bpf_object__load_vmlinux_btf such that we are
able to load BTF on demand.

Let's start with the real problem, not a solution. Do you have
specific use case where you need bpf_object__load_vmlinux_btf()? It
might not do anything if none of BPF programs in the object requires
BTF, because it's very much tightly coupled with loading bpf_object as
a whole model. I'd like to understand what you are after with this,
before exposing internal implementation details as an API.

Signed-off-by: Daniel Xu <redacted>
---
 tools/lib/bpf/libbpf.c   | 2 +-
 tools/lib/bpf/libbpf.h   | 1 +
 tools/lib/bpf/libbpf.map | 1 +
 3 files changed, 3 insertions(+), 1 deletion(-)

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