CONFIG_TRACE_EVAL_MAP_FILE: Show eval mappings for trace events

General informations

The Linux kernel configuration item CONFIG_TRACE_EVAL_MAP_FILE:

• prompt: Show eval mappings for trace events
• type: bool
• depends on: CONFIG_TRACING
• defined in kernel/trace/Kconfig
• found in Linux kernels: 4.13–4.20, 5.0–5.19, 6.0–6.12

Help text

The "print fmt" of the trace events will show the enum/sizeof names instead of their values. This can cause problems for user space tools that use this string to parse the raw data as user space does not know how to convert the string to its value.

To fix this, there's a special macro in the kernel that can be used to convert an enum/sizeof into its value. If this macro is used, then the print fmt strings will be converted to their values.

If something does not get converted properly, this option can be used to show what enums/sizeof the kernel tried to convert.

This option is for debugging the conversions. A file is created in the tracing directory called "eval_map" that will show the names matched with their values and what trace event system they belong too.

Normally, the mapping of the strings to values will be freed after boot up or module load. With this option, they will not be freed, as they are needed for the "eval_map" file. Enabling this option will increase the memory footprint of the running kernel.

If unsure, say N.

Hardware

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This page is automaticly generated with free (libre, open) software lkddb(see lkddb-sources).

The data is retrived from:

• Linux kernel
• Linux Kernel Driver DataBase (LKDDb)

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