Frequently Asked Questions
What is ReadyKernel?ReadyKernel is a kpatch-based service that offers a more convenient, rebootless alternative to updating the kernel the usual way and allows you not to wait for scheduled server downtime to apply critical security updates.
How much does ReadyKernel cost?ReadyKernel is free for all paid customers of Virtuozzo.
Is there any support for ReadyKernel?ReadyKernel is supported by Virtuozzo. You can get support if you have an active subscription. See: virtuozzo.com/support.
Do I have to reboot my server after installing a ReadyKernel patch?There is no need to reboot the server after installing any ReadyKernel patches or tools.
Which kernels are supported by ReadyKernel?The list of kernels for each supported Linux distribution is available at readykernel.com.
How can I check if my server is affected by any security issues fixed with ReadyKernel?
You can test your environment with a simple ReadyKernel scanner utility available here: readykernel-scan.
To scan your server, run
# wget http://repo.virtuozzo.com/readykernel-utils/readykernel-scan; python readykernel-scan
Is using ReadyKernel safe?ReadyKernel patches will not be installed on and applied to your host if the kernel is incompatible with the patch. Moreover, if ReadyKernel detects that it is unsafe to apply the patch at the moment, the patch will not be applied and the system will remain in its original state.
What about regular OS updates?ReadyKernel only keeps the kernel secure. User space packages are not affected by ReadyKernel and should be updated the usual way.
How can I install ReadyKernel and update the kernel with it?
The software components required by ReadyKernel are automatically installed together with ReadyKernel updates. To get ReadyKernel updates for all installed kernels, execute
# readykernel update
If you would like to install the latest ReadyKernel update for the currently running kernel only, it is possible too:
# yum install readykernel-patch-$(uname -r)
How can I uninstall ReadyKernel?
To uninstall ReadyKernel, run
# yum remove 'readykernel*' 'kpatch*'
How can I enable automatic installation of ReadyKernel updates?
# readykernel autoupdate enable
Alternatively, you can add the following command to the cron schedule:
# yum install -y readykernel-patch-$(uname -r)
How can I list ReadyKernel updates applied to the kernel?
To display information about the currently applied kernel patches, run
# readykernel info
readykernel update complains that another live patching system has been detected. What should I do?
On CentOS, readykernel update may output the following or a similar error in some cases:
Error: Another live patching system detected: 'kpatch' package is installed. It may be unsafe to use both that system and ReadyKernel at the same time.
It is not recommended to have both ReadyKernel and other live patching systems installed on the same machine. If you intend to use ReadyKernel there, please remove the packages mentioned in that error message first.
# yum remove 'kpatch'
Is ReadyKernel software released under open source license?To perform most operations, ReadyKernel uses customized Kpatch tools. The source code is available at src.openvz.org/projects/UP/repos/kpatch/browse under the GPL2 license. Binary patches are a part of the paid service and are not publicly available.