Comment 4 for bug 1917958

It looks like a fix for this issue is already in the 137 kernel.

The change log for the -136 update shows a single change related to Hyper-V, and that change broke the ability to open /dev/fb0 and mmap it, which is what the graphic desktop will do. Running in non-graphics mode with just a shell and with ‘ssh’ access works fine, which is why Azure VMs didn’t see the issue.

The original change went into the mainline Linux kernel version 5.10, and the change is correct there. It provides a significant performance improvement for the Hyper-V frame buffer. So we wanted it backported to the older releases. Unfortunately, a straight backport breaks in kernel version 5.4 and earlier. The backport needs a minor modification to work correctly 4.15, but we didn’t spot that immediately, mostly because we rarely use graphic desktops.

The 4.15.0-137.141 kernel in the queue already, so this issue will be resolved and it only affects 136 - not 135 or 137.