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4ddbd0b7 PP |
1 | lttng-ust-dl(3) |
2 | =============== | |
3 | :object-type: library | |
4 | ||
5 | ||
6 | NAME | |
7 | ---- | |
8 | lttng-ust-dl - Dynamic linker tracing (LTTng-UST helper) | |
9 | ||
10 | ||
11 | SYNOPSIS | |
12 | -------- | |
13 | Launch your application by preloading `liblttng-ust-dl.so`: | |
14 | ||
15 | [role="term"] | |
16 | [verse] | |
17 | *LD_PRELOAD=liblttng-ust-dl.so* my-app | |
18 | ||
19 | ||
20 | DESCRIPTION | |
21 | ----------- | |
22 | When the `liblttng-ust-dl.so` library is preloaded before a given | |
23 | application starts, it causes all calls to man:dlopen(3) and | |
24 | man:dlclose(3) in said application to be traced with LTTng-UST (see | |
25 | man:lttng-ust(3)). | |
26 | ||
27 | See man:lttng(1) to learn more about how to control LTTng tracing | |
28 | sessions. | |
29 | ||
d1194248 PP |
30 | IMPORTANT: This LTTng-UST helper can also emit _shared library |
31 | load/unload_ events (see _Shared library load/unload tracking_ in | |
32 | man:lttng-ust(3)). You should :not: use the event records generated by | |
33 | this LTTng-UST helper (prefixed with `lttng_ust_dl:`) to track the | |
34 | loading and unloading of shared libraries, especially in situations | |
35 | where a dynamically loaded library loads its own dependencies. Instead, | |
36 | do preload `liblttng-ust-dl.so`, but use the shared library load/unload | |
37 | event records, which are more reliable, for your tracking analysis. | |
38 | ||
39 | The following LTTng-UST events are available when using this library. | |
40 | ||
4ddbd0b7 PP |
41 | |
42 | `lttng_ust_dl:dlopen`:: | |
43 | Emitted when man:dlopen(3) is called. | |
44 | + | |
45 | Fields: | |
46 | + | |
47 | [options="header"] | |
8902dadc PP |
48 | |=== |
49 | |Field name |Description | |
50 | ||
51 | |`baddr` | |
d01f365a | 52 | |Base address of loaded library. |
8902dadc PP |
53 | |
54 | |`memsz` | |
d01f365a | 55 | |Size of loaded library in memory. |
8902dadc PP |
56 | |
57 | |`path` | |
d01f365a | 58 | |Path to loaded library file. |
8902dadc | 59 | |=== |
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60 | |
61 | `lttng_ust_dl:dlclose`:: | |
62 | Emitted when man:dlclose(3) is called. | |
63 | + | |
64 | Fields: | |
65 | + | |
66 | [options="header"] | |
8902dadc PP |
67 | |=== |
68 | |Field name |Description | |
69 | ||
70 | |`baddr` | |
d01f365a | 71 | |Base address of loaded library. |
8902dadc | 72 | |=== |
4ddbd0b7 PP |
73 | |
74 | `lttng_ust_dl:debug_link`:: | |
75 | Emitted when debug link information is found when loading a library | |
76 | with man:dlopen(3). See | |
77 | https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html[Debugging Information in Separate Files] | |
78 | for more information about debug links. | |
79 | + | |
80 | Fields: | |
81 | + | |
82 | [options="header"] | |
8902dadc PP |
83 | |=== |
84 | |Field name |Description | |
85 | ||
86 | |`baddr` | |
d01f365a | 87 | |Base address of loaded library. |
8902dadc PP |
88 | |
89 | |`filename` | |
d01f365a | 90 | |Debug link file name. |
8902dadc PP |
91 | |
92 | |`crc` | |
d01f365a | 93 | |Debug link file's CRC. |
8902dadc | 94 | |=== |
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95 | |
96 | `lttng_ust_dl:build_id`:: | |
97 | Emitted when a build ID is found when loading a library | |
98 | with man:dlopen(3). See | |
99 | https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html[Debugging Information in Separate Files] | |
100 | for more information about build IDs. | |
101 | + | |
102 | Fields: | |
103 | + | |
104 | [options="header"] | |
8902dadc PP |
105 | |=== |
106 | |Field name |Description | |
107 | ||
108 | |`baddr` | |
d01f365a | 109 | |Base address of loaded library. |
8902dadc PP |
110 | |
111 | |`build_id` | |
d01f365a | 112 | |Build ID. |
8902dadc | 113 | |=== |
4ddbd0b7 PP |
114 | |
115 | ||
116 | include::common-footer.txt[] | |
117 | ||
118 | include::common-copyrights.txt[] | |
119 | ||
120 | include::common-authors.txt[] | |
121 | ||
122 | ||
123 | SEE ALSO | |
124 | -------- | |
125 | man:lttng-ust(3), | |
126 | man:dlopen(3), | |
127 | man:lttng(1) |