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authorPaul E. McKenney <paulmck@kernel.org>2022-08-02 20:39:12 +0300
committerAlexei Starovoitov <ast@kernel.org>2022-08-04 23:17:24 +0300
commit62fc770d90ef5a92931deb477c384f82be122a18 (patch)
tree32eeb350c15080dca3e91d23dcb60ddb72cdc177 /Documentation/bpf
parentb9b738eeafe54d960ccb240fc1b0c5031a0d76f5 (diff)
downloadlinux-62fc770d90ef5a92931deb477c384f82be122a18.tar.xz
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 <paulmck@kernel.org> Link: https://lore.kernel.org/r/20220802173913.4170192-2-paulmck@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'Documentation/bpf')
-rw-r--r--Documentation/bpf/bpf_design_QA.rst12
1 files changed, 12 insertions, 0 deletions
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.