Re: [RFC PATCH 04/10] liveupdate: flb: allow getting FLB data in early boot

Pasha Tatashin
2025-12-20T15:12:11Z

> > [Follow-up from LPC discussion]
> >
> > This patch is not needed, you can use liveupdate_flb_get_incoming()
> > directly in early boot. The main concern is that we take mutex in that
> > function, but that I think is safe. The might_sleep() has the proper
> > handling to be called early in boot, it has "system_state ==
> > SYSTEM_BOOTING" check to silence warning during boot.
>
> Right. I will give it a try. For hugetlb, this works fine since it
> doesn't really need to do much in FLB retrieve anyway, it just needs to
> parse some data structures.
>
> If other subsystems end up needing a two-part retrieve, one in early
> boot and one later, then I think it would be a good idea to model that
> properly instead of leaving it up to the subsystem to manage it.
>
> Anyway, that isn't a real problem today so let's look at it when it does
> show up.

FLB has exactly one .retrieve() lifecycle event. Once called, the data
is considered fully available and cached in private->incoming.obj.

If a subsystem has a requirement where it needs a specific state
available very early and other state available much later, the clean
solution is simply to register two separate FLBs.

Pasha