Lots of use cases - Rolling kernel upgrade

Posted Sep 22, 2025 8:10 UTC (Mon) by rhbvkleef (subscriber, #154505)
In reply to: Lots of use cases by geofft
Parent article: Multiple kernels on a single system

I think another enticing use-case would be a kind of "rolling" kernel upgrade where we can start a newer kernel on a subset of cores, and migrate our userspace over to it gradually, before killing the old kernel.

Lots of use cases - Rolling kernel upgrade

Posted Sep 25, 2025 12:55 UTC (Thu) by Karellen (subscriber, #67644) [Link]

I'm not sure having multiple kernels accessing the same block device/filesystem is going to work very well. If it were going to work at all you'd probably need a separate virtual filesystem driver for the new kernel, which talks to a server on the old, and then once the old kernel is ready to unmount the filesystem do a switcheroo-handover type thing. The new kernel would have to swap out the virtual filesystem driver for the real ext4/btrfs/... and start accessing the "real" inodes directly?