Windows 11 24H2: Is Microsoft planning "hotpatching" (Update installation without reboot)?

Windows[German]A small addendum from last week regarding the development of Windows 11. There are reports (rumors) that the upcoming Windows 11 version 24H2 could or should get something like "hotpatching". This would mean that updates can be installed and take effect without the need for a reboot. However, the concept, as it currently appears to me, has some limitations that you should be aware of.

What is hotpatching?

The term hotpatching describes a technology, where security updates are installed without requiring a reboot. In Windows a reboot is required for system updates to take effect on the kernel. That's mandatory, because the relevant files are in system access and cannot be updated.

Only when the system is restarted are the updates completed, the kernel files updated and then the changed functions loaded into memory for execution when the system is restarted in order to take effect from then on. In Linux, mechanisms are known to realise hot patching, in which corrections are taken into account in memory and included in the system files the next time the system is restarted.

Especially with servers, a "down time" due to a restart is rather undesirable. Microsoft has therefore been working for some time on making this hotpatching available for Windows and kernel functions.

In the support article Hotpatch for virtual machines Microsoft describes the chosen approach for hotpatching as a method for installing operating system security updates on supported virtual machines (VMs) under Windows Server Datacenter: Azure Edition without requiring a reboot after installation. The in-memory code of running processes is patched without the process having to be restarted.

Rumor: Windows 11 24H2 shall get hotpatching

Windows Central took up the topic a few days ago in the article Microsoft wants to update your Windows 11 PC without forcing you to reboot and reported on Microsoft's plans. In a nutshell:

  • Microsoft is testing a new update method for Windows 11 that will allow the operating system to install critical updates without the otherwise required reboot.
  • This technology, known as hotpatching, which is already used in the Windows Server scenarios mentioned above and for the Xbox, is expected to arrive with Windows 11 version 24H2, which is expected in autumn 2024.

Zack Bowden refers to sources at Microsoft in his Windows Central article, according to which the developers intend to use hot patching in Windows 11 to provide monthly security updates without the user having to reboot. However, there is one restriction: a restart is required every few months.

  • Specifically, it is planned that only four monthly security updates per year will require a restart, namely in January, April, July and October.
    The other months will be supplied via hot patching, which should then not require a restart.
  • However, according to the premise that "all theory is grey", there are also restrictions there. Major security updates, bug-fix updates to rectify errors and function updates, which can be provided at any time if required, also require a restart outside the months specified above.

According to the premise "All theory is grey", however, there are limitations there too. Major security updates, bug-fix updates to rectify errors and function updates, which can be provided at any time if required, and also require a restart outside the months specified above.

It is therefore possible that "a bit of hotpatching" is planned, which is now being celebrated on the web. The colleagues from deskmodder.de have provided some more clues in this article, because Microsoft tried out hotpatching with a few testers during the Windows 11 Dev-Insider Preview.

For me, the exciting questions are: "Will this feature come in the final version of Windows 11?". Till now it's just an a/b test in an insider preview, and Microsoft hasn't mentioned it with a word. And if it made it into the final: "How well does that work and which systems really get it?" – overall: restarting a Windows 11 client is not such a big deal – unless the install process runs indefinitely and there are malfunctions or a rollback at the end. It will be interesting to see how these oddities are resolved.

According to Zack Bowden, hotpatching is expected to come to the Intel/AMD x86 platform in 2024. The ARM64 systems will not receive support for hotpatching until 2025. The prerequisite is that Microsoft's schedules hold. It is also unclear whether all Windows 11 users will receive the function. It is conceivable that this could only be implemented in the commercial Windows 11 editions such as Enterprise, Education and Windows 365. All we can say at the moment is: Microsoft "sources" has spread some kind of rumor, we'll have to wait and see what comes along the corner.

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One Response to Windows 11 24H2: Is Microsoft planning "hotpatching" (Update installation without reboot)?

  1. Chris Pugson says:

    I have a Dell Vostro 3268 which is running Windows 11 on Seventh Generation hardware. I am running Windows 11 22H2. On attempting to update to 23H2, I have discovered that Microsoft has ruled that Windows 11 23H2 does not support Seventh Generation technology equipped systems. Microsoft never advertised that it had designated Seventh Generation technology as close to 'end of life' and so I was not warned against acquiring a short life Windows 11 system.

    Microsoft is hanging the users of hundreds of millions of its Windows systems out to dry. Google is offering ChromeOS Flex to Windows users. I hope that ChromeOS Flex is a roaring success and that Microsoft bitterly regrets its poor judgement.

    This home user does not trust Microsoft not to make my Windows systems obsolete at short notice.

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