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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>
This commit is contained in:
Paul E. McKenney 2022-08-02 10:39:12 -07:00 committed by Alexei Starovoitov
parent b9b738eeaf
commit 62fc770d90
1 changed files with 12 additions and 0 deletions
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Documentation/bpf/bpf_design_QA.rst
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@ -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.