From 62fc770d90ef5a92931deb477c384f82be122a18 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 2 Aug 2022 10:39:12 -0700 Subject: bpf: Update bpf_design_QA.rst to clarify that attaching to functions is not ABI This patch updates bpf_design_QA.rst to clarify that the ability to attach a BPF program to an arbitrary function in the kernel does not make that function become part of the Linux kernel's ABI. [ paulmck: Apply Daniel Borkmann feedback. ] Signed-off-by: Paul E. McKenney Link: https://lore.kernel.org/r/20220802173913.4170192-2-paulmck@kernel.org Signed-off-by: Alexei Starovoitov --- Documentation/bpf/bpf_design_QA.rst | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'Documentation/bpf/bpf_design_QA.rst') diff --git a/Documentation/bpf/bpf_design_QA.rst b/Documentation/bpf/bpf_design_QA.rst index 2ed9128cfbec..a06ae8a828e3 100644 --- a/Documentation/bpf/bpf_design_QA.rst +++ b/Documentation/bpf/bpf_design_QA.rst @@ -279,3 +279,15 @@ cc (congestion-control) implementations. If any of these kernel functions has changed, both the in-tree and out-of-tree kernel tcp cc implementations have to be changed. The same goes for the bpf programs and they have to be adjusted accordingly. + +Q: Attaching to arbitrary kernel functions is an ABI? +----------------------------------------------------- +Q: BPF programs can be attached to many kernel functions. Do these +kernel functions become part of the ABI? + +A: NO. + +The kernel function prototypes will change, and BPF programs attaching to +them will need to change. The BPF compile-once-run-everywhere (CO-RE) +should be used in order to make it easier to adapt your BPF programs to +different versions of the kernel. -- cgit v1.2.3