Re: [PATCH v4 00/30] Live Update Orchestrator

On Tue, Oct 07, 2025 at 01:10:30PM -0400, Pasha Tatashin wrote:

1. Add three more callbacks to liveupdate_file_ops:
/*
 * Optional. Called by LUO during first get global state call.
 * The handler should allocate/KHO preserve its global state object and return a
 * pointer to it via 'obj'. It must also provide a u64 handle (e.g., a physical
 * address of preserved memory) via 'data_handle' that LUO will save.
 * Return: 0 on success.
 */
int (*global_state_create)(struct liveupdate_file_handler *h,
                           void **obj, u64 *data_handle);

/*
 * Optional. Called by LUO in the new kernel
 * before the first access to the global state. The handler receives
 * the preserved u64 data_handle and should use it to reconstruct its
 * global state object, returning a pointer to it via 'obj'.
 * Return: 0 on success.
 */
int (*global_state_restore)(struct liveupdate_file_handler *h,
                            u64 data_handle, void **obj);

It shouldn't be a "push" like this. Everything has a certain logical point
when it will need the luo data, it should be coded to 'pull' the data
right at that point.

/*
 * Optional. Called by LUO after the last
 * file for this handler is unpreserved or finished. The handler
 * must free its global state object and any associated resources.
 */
void (*global_state_destroy)(struct liveupdate_file_handler *h, void *obj);

I'm not sure a callback here is a good idea, the users are synchronous
at early boot, they should get their data and immediately process it
within the context of the caller. A 'unpack' callback does not seem so
useful to me.

The get/put global state data:

/* Get and lock the data with file_handler scoped lock */
int liveupdate_fh_global_state_get(struct liveupdate_file_handler *h,
                                   void **obj);

/* Unlock the data */
void liveupdate_fh_global_state_put(struct liveupdate_file_handler *h);

Maybe lock/unlock if it is locking.

It seems like a good direction overall. Really need to see how it
works with some examples

Jason