Re: [PATCH v5 02/22] liveupdate: luo_core: integrate with KHO

[Mike Rapoport <rppt@kernel.org>]

On Fri, Nov 07, 2025 at 04:03:00PM -0500, Pasha Tatashin wrote:
> Integrate the LUO with the KHO framework to enable passing LUO state
> across a kexec reboot.
> 
> When LUO is transitioned to a "prepared" state, it tells KHO to
> finalize, so all memory segments that were added to KHO preservation
> list are getting preserved. After "Prepared" state no new segments
> can be preserved. If LUO is canceled, it also tells KHO to cancel the
> serialization, and therefore, later LUO can go back into the prepared
> state.
> 
> This patch introduces the following changes:
> - During the KHO finalization phase allocate FDT blob.
> - Populate this FDT with a LUO compatibility string ("luo-v1").
> 
> LUO now depends on `CONFIG_KEXEC_HANDOVER`. The core state transition
> logic (`luo_do_*_calls`) remains unimplemented in this patch.
> 
> Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>

...

> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index c6812b4dbb2e..20c850a52167 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -21,6 +21,7 @@
>  #include <linux/buffer_head.h>
>  #include <linux/kmemleak.h>
>  #include <linux/kfence.h>
> +#include <linux/liveupdate.h>
>  #include <linux/page_ext.h>
>  #include <linux/pti.h>
>  #include <linux/pgtable.h>
> @@ -2703,6 +2704,9 @@ void __init mm_core_init(void)
>  	 */
>  	kho_memory_init();
>  
> +	/* Live Update should follow right after KHO is initialized */
> +	liveupdate_init();
> +

Why do you think it should be immediately after kho_memory_init()?
Any reason this can't be called from start_kernel() or even later as an
early_initcall() or core_initall()?

>  	memblock_free_all();
>  	mem_init();
>  	kmem_cache_init();
> -- 
> 2.51.2.1041.gc1ab5b90ca-goog
> 
> 

-- 
Sincerely yours,
Mike.