Kernel Patches Test Suspend States at Runtime
Two patches by Rafael J. Wysocki give users the ability to test suspend and hibernation modes at runtime to detect errors.
The first patch gives users the ability to test the suspend code (suspend to disk) without actually switching to suspend mode. This is a useful approach to discovering driver issues says the developer. The second patch modifies the current hibernation function (Suspend to RAM) source code to achieve the same objective. According to Wysocki, this works better than the current test modes as his code can also test globabl ACPI methods.
The test options add a new "/sys/power/pm_test_level" attribute which accepts numbers between 1 and 5. Each of these values simulates a different suspend or hibernation code level. Wysocki explains the individual values as follows. 5 test the freezing of individual processes. 4 additionally tests suspending of devices. Besides suspending processes and devices, 3 additionally tests platform global methods. 2 adds disabling of nonboot CPUs, and 1 simulates full system suspend.
The developer adds: "if a suspend is started by normal means, the suspend core will perform its normal operations up to the point indicated by the test level. Next, it will wait for 5 seconds and carry out the resume operations needed to transition the system back to the fully functional state". To avoid using the text system, you can set "pm_test_level" to 0. Wysocki’s third patch adds information on his test systems to the documentation.
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
Canonical Releases Ubuntu 24.04
After a brief pause because of the XZ vulnerability, Ubuntu 24.04 is now available for install.
-
Linux Servers Targeted by Akira Ransomware
A group of bad actors who have already extorted $42 million have their sights set on the Linux platform.
-
TUXEDO Computers Unveils Linux Laptop Featuring AMD Ryzen CPU
This latest release is the first laptop to include the new CPU from Ryzen and Linux preinstalled.
-
XZ Gets the All-Clear
The back door xz vulnerability has been officially reverted for Fedora 40 and versions 38 and 39 were never affected.
-
Canonical Collaborates with Qualcomm on New Venture
This new joint effort is geared toward bringing Ubuntu and Ubuntu Core to Qualcomm-powered devices.
-
Kodi 21.0 Open-Source Entertainment Hub Released
After a year of development, the award-winning Kodi cross-platform, media center software is now available with many new additions and improvements.
-
Linux Usage Increases in Two Key Areas
If market share is your thing, you'll be happy to know that Linux is on the rise in two areas that, if they keep climbing, could have serious meaning for Linux's future.
-
Vulnerability Discovered in xz Libraries
An urgent alert for Fedora 40 has been posted and users should pay attention.
-
Canonical Bumps LTS Support to 12 years
If you're worried that your Ubuntu LTS release won't be supported long enough to last, Canonical has a surprise for you in the form of 12 years of security coverage.
-
Fedora 40 Beta Released Soon
With the official release of Fedora 40 coming in April, it's almost time to download the beta and see what's new.