CONFIG_PM_TRACE:

General informations

The Linux kernel configuration item CONFIG_PM_TRACE has multiple definitions:

found in kernel/power/Kconfig

The configuration item CONFIG_PM_TRACE:

• prompt:
• type: bool
• depends on: (none)
• defined in kernel/power/Kconfig
• found in Linux kernels: 2.6.25–2.6.39, 3.0–3.19, 4.0–4.20, 5.0–5.19, 6.0–6.8, 6.9-rc+HEAD

Help text

This enables code to save the last PM event point across reboot. The architecture needs to support this, x86 for example does by saving things in the RTC, see below.

The architecture specific code must provide the extern functions from <linux/resume-trace.h> as well as the <asm/resume-trace.h> header with a TRACE_RESUME() macro.

The way the information is presented is architecture- dependent, x86 will print the information during a late_initcall.

Suspend/resume event tracing found in kernel/power/Kconfig

The configuration item CONFIG_PM_TRACE:

• prompt: Suspend/resume event tracing
• type: bool
• depends on: CONFIG_PM_DEBUG && CONFIG_X86 && CONFIG_PM_SLEEP && CONFIG_EXPERIMENTAL
• defined in kernel/power/Kconfig
• found in Linux kernels: 2.6.18–2.6.24

Help text

This enables some cheesy code to save the last PM event point in the RTC across reboots, so that you can debug a machine that just hangs during suspend (or more commonly, during resume).

To use this debugging feature you should attempt to suspend the machine, then reboot it, then run

dmesg -s 1000000 | grep 'hash matches'

CAUTION: this option will cause your machine's real-time clock to be set to an invalid time after a resume.

Hardware

LKDDb

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• (none)

Sources

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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