On Tue, May 20, 2025 at 3:25 AM Mike Rapoport <rppt@xxxxxxxxxx> wrote: > > Hi Pasha, > > On Thu, May 15, 2025 at 06:23:04PM +0000, Pasha Tatashin wrote: > > This v2 series introduces the LUO, a kernel subsystem designed to > > facilitate live kernel updates with minimal downtime, > > particularly in cloud delplyoments aiming to update without fully > > disrupting running virtual machines. > > > > This series builds upon KHO framework [1] by adding programmatic > > control over KHO's lifecycle and leveraging KHO for persisting LUO's > > own metadata across the kexec boundary. The git branch for this series > > can be found at: > > https://github.com/googleprodkernel/linux-liveupdate/tree/luo/rfc-v2 > > > > What is Live Update? > > Live Update is a specialized reboot process where selected kernel > > resources (memory, file descriptors, and eventually devices) are kept > > operational or their state preserved across a kernel transition (e.g., > > via kexec). For certain resources, DMA and interrupt activity might > > continue with minimal interruption during the kernel reboot. > > > > LUO v2 Overview: > > LUO v2 provides a framework for coordinating live updates. It features: > > State Machine: Manages the live update process through states: > > NORMAL, PREPARED, FROZEN, UPDATED. > > > > KHO Integration: > > > > LUO programmatically drives KHO's finalization and abort sequences. > > KHO's debugfs interface is now optional configured via > > CONFIG_KEXEC_HANDOVER_DEBUG. > > > > LUO preserves its own metadata via KHO's kho_add_subtree and > > kho_preserve_phys() mechanisms. > > I've only had time to skip through the patches, one thing that came to mind > was that since LUO is quite tightly coupled with KHO maybe we'll put them > together in, say, kernel/liveupdate? Thank you Mike, yes, a good idea, I also thought that it would make sense for them to be in the same place, but initially I thought perhaps KHO should be moved to misc/liveupdate/, but since it is already landing in kernel/kexec_*, and it works with a bunch of core kernel subsystems it makes sense to move LUO and KHO together under kernel/liveupdate/ Pasha
