1 .. SPDX-License-Identifier: (GPL-2.0-only OR B 1 .. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2 2
3 =============== 3 ===============
4 bpftool-feature 4 bpftool-feature
5 =============== 5 ===============
6 ---------------------------------------------- 6 -------------------------------------------------------------------------------
7 tool for inspection of eBPF-related parameters 7 tool for inspection of eBPF-related parameters for Linux kernel or net device
8 ---------------------------------------------- 8 -------------------------------------------------------------------------------
9 9
10 :Manual section: 8 10 :Manual section: 8
11 11
12 .. include:: substitutions.rst 12 .. include:: substitutions.rst
13 13
14 SYNOPSIS 14 SYNOPSIS
15 ======== 15 ========
16 16
17 **bpftool** [*OPTIONS*] **feature** *COMMAND* 17 **bpftool** [*OPTIONS*] **feature** *COMMAND*
18 18
19 *OPTIONS* := { |COMMON_OPTIONS| } 19 *OPTIONS* := { |COMMON_OPTIONS| }
20 20
21 *COMMANDS* := { **probe** | **help** } 21 *COMMANDS* := { **probe** | **help** }
22 22
23 FEATURE COMMANDS 23 FEATURE COMMANDS
24 ================ 24 ================
25 25
26 | **bpftool** **feature probe** [*COMPONENT*] 26 | **bpftool** **feature probe** [*COMPONENT*] [**full**] [**unprivileged**] [**macros** [**prefix** *PREFIX*]]
27 | **bpftool** **feature list_builtins** *GROUP 27 | **bpftool** **feature list_builtins** *GROUP*
28 | **bpftool** **feature help** 28 | **bpftool** **feature help**
29 | 29 |
30 | *COMPONENT* := { **kernel** | **dev** *NAME* 30 | *COMPONENT* := { **kernel** | **dev** *NAME* }
31 | *GROUP* := { **prog_types** | **map_types** 31 | *GROUP* := { **prog_types** | **map_types** | **attach_types** | **link_types** | **helpers** }
32 32
33 DESCRIPTION 33 DESCRIPTION
34 =========== 34 ===========
35 bpftool feature probe [kernel] [full] [macros 35 bpftool feature probe [kernel] [full] [macros [prefix *PREFIX*]]
36 Probe the running kernel and dump a number 36 Probe the running kernel and dump a number of eBPF-related parameters, such
37 as availability of the **bpf**\ () system 37 as availability of the **bpf**\ () system call, JIT status, eBPF program
38 types availability, eBPF helper functions 38 types availability, eBPF helper functions availability, and more.
39 39
40 By default, bpftool **does not run probes* 40 By default, bpftool **does not run probes** for **bpf_probe_write_user**\
41 () and **bpf_trace_printk**\() helpers whi 41 () and **bpf_trace_printk**\() helpers which print warnings to kernel logs.
42 To enable them and run all probes, the **f 42 To enable them and run all probes, the **full** keyword should be used.
43 43
44 If the **macros** keyword (but not the **- 44 If the **macros** keyword (but not the **-j** option) is passed, a subset
45 of the output is dumped as a list of **#de 45 of the output is dumped as a list of **#define** macros that are ready to
46 be included in a C header file, for exampl 46 be included in a C header file, for example. If, additionally, **prefix**
47 is used to define a *PREFIX*, the provided 47 is used to define a *PREFIX*, the provided string will be used as a prefix
48 to the names of the macros: this can be us 48 to the names of the macros: this can be used to avoid conflicts on macro
49 names when including the output of this co 49 names when including the output of this command as a header file.
50 50
51 Keyword **kernel** can be omitted. If no p 51 Keyword **kernel** can be omitted. If no probe target is specified, probing
52 the kernel is the default behaviour. 52 the kernel is the default behaviour.
53 53
54 When the **unprivileged** keyword is used, 54 When the **unprivileged** keyword is used, bpftool will dump only the
55 features available to a user who does not 55 features available to a user who does not have the **CAP_SYS_ADMIN**
56 capability set. The features available in 56 capability set. The features available in that case usually represent a
57 small subset of the parameters supported b 57 small subset of the parameters supported by the system. Unprivileged users
58 MUST use the **unprivileged** keyword: Thi 58 MUST use the **unprivileged** keyword: This is to avoid misdetection if
59 bpftool is inadvertently run as non-root, 59 bpftool is inadvertently run as non-root, for example. This keyword is
60 unavailable if bpftool was compiled withou 60 unavailable if bpftool was compiled without libcap.
61 61
62 bpftool feature probe dev *NAME* [full] [macro 62 bpftool feature probe dev *NAME* [full] [macros [prefix *PREFIX*]]
63 Probe network device for supported eBPF fe 63 Probe network device for supported eBPF features and dump results to the
64 console. 64 console.
65 65
66 The keywords **full**, **macros** and **pr 66 The keywords **full**, **macros** and **prefix** have the same role as when
67 probing the kernel. 67 probing the kernel.
68 68
69 bpftool feature list_builtins *GROUP* 69 bpftool feature list_builtins *GROUP*
70 List items known to bpftool. These can be 70 List items known to bpftool. These can be BPF program types
71 (**prog_types**), BPF map types (**map_typ 71 (**prog_types**), BPF map types (**map_types**), attach types
72 (**attach_types**), link types (**link_typ 72 (**attach_types**), link types (**link_types**), or BPF helper functions
73 (**helpers**). The command does not probe 73 (**helpers**). The command does not probe the system, but simply lists the
74 elements that bpftool knows from compilati 74 elements that bpftool knows from compilation time, as provided from libbpf
75 (for all object types) or from the BPF UAP 75 (for all object types) or from the BPF UAPI header (list of helpers). This
76 can be used in scripts to iterate over BPF 76 can be used in scripts to iterate over BPF types or helpers.
77 77
78 bpftool feature help 78 bpftool feature help
79 Print short help message. 79 Print short help message.
80 80
81 OPTIONS 81 OPTIONS
82 ======= 82 =======
83 .. include:: common_options.rst 83 .. include:: common_options.rst
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