[PATCH v3 bpf 2/3] bpf: Update bpf_design_QA.rst to clarify that attaching to functions is not ABI
From: "Paul E. McKenney" <paulmck@kernel.org>
Date: 2022-08-02 17:39:19
Also in:
bpf, linux-doc
Subsystem:
bpf [general] (safe dynamic programs and tools), documentation, the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Jonathan Corbet, Linus Torvalds
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 <paulmck@kernel.org> --- Documentation/bpf/bpf_design_QA.rst | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/Documentation/bpf/bpf_design_QA.rst b/Documentation/bpf/bpf_design_QA.rst
index 2ed9128cfbec8..a06ae8a828e3d 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.
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2.31.1.189.g2e36527f23