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Merge branch 'bpf-doc-updates'

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Daniel Borkmann says:

====================
Two trivial doc follow-ups to i) remove deprecated kern_version
mentioning in the design qa and ii) to mention stand-alone build
and license of libbpf. Thanks!
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov 2019-01-07 15:52:00 -08:00
commit 2dc0f02da1
2 changed files with 19 additions and 6 deletions
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11
Documentation/bpf/bpf_design_QA.rst
View File

@ -157,12 +157,11 @@ Q: Does BPF have a stable ABI?
------------------------------
A: YES. BPF instructions, arguments to BPF programs, set of helper
functions and their arguments, recognized return codes are all part
of ABI. However when tracing programs are using bpf_probe_read() helper
to walk kernel internal datastructures and compile with kernel
internal headers these accesses can and will break with newer
kernels. The union bpf_attr -> kern_version is checked at load time
to prevent accidentally loading kprobe-based bpf programs written
for a different kernel. Networking programs don't do kern_version check.
of ABI. However there is one specific exception to tracing programs
which are using helpers like bpf_probe_read() to walk kernel internal
data structures and compile with kernel internal headers. Both of these
kernel internals are subject to change and can break with newer kernels
such that the program needs to be adapted accordingly.
Q: How much stack space a BPF program uses?
-------------------------------------------

14
tools/lib/bpf/README.rst
View File

@ -132,6 +132,20 @@ For example, if current state of ``libbpf.map`` is:
Format of version script and ways to handle ABI changes, including
incompatible ones, described in details in [1].
Stand-alone build
=================
Under https://github.com/libbpf/libbpf there is a (semi-)automated
mirror of the mainline's version of libbpf for a stand-alone build.
However, all changes to libbpf's code base must be upstreamed through
the mainline kernel tree.
License
=======
libbpf is dual-licensed under LGPL 2.1 and BSD 2-Clause.
Links
=====