With Linux 6.17 out of the door, the merge window for Linux 6.18 has opened. With Linux 6.18, the Linux kernel is getting further enhancements for Microsoft’s Hyper-V virtualization support. One of the main improvements is that the Hyper-V guest entry code has been unified for both KVM and Microsoft Hyper-V; this simplification could make the code easier to maintain.
Another new feature is that Kexec and Kdump are now supported within Azure Confidential Virtual Machines. Kexec allows Linux systems to boot a new kernel quickly without a full restart while Kdump can snapshot the system’s memory when the system crashes to help figure out why a crash has happened. With these changes, even in super-secure, encrypted CVMs, you can use Kexec/Kdump. This allows developers to debug crashes properly in confidential environments on Azure.
Aside from adding features, Microsoft has formally deprecated the Hyper-V frame-buffer driver “hyperv_fb.” The driver is being phased out in favor of the Hyper-V Direct Rendering Manager (DRM) driver. According to Phoronix, DRM/KMS drivers are far better than the older Linux FB drivers.
Aside from the aforementioned changes, there are a variety of other updates to Hyper-V landing in Linux 6.18. One of them is that the infrastructure has been cleaned up for added efficiency. The Hyper-V MSI domain has been updated to change how Hyper-V managed hardware interrupt requests, modernizing the mechanism for better efficiency.
These and the rest of the changes to Linux 6.18 will be tested over the next two months to ensure their stability before they’re pushed out to the public.