Re: [PATCH 28/37] xen/arm: stub memory hotplug access helpers for Arm

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 23 Sep 2021, Wei Chen wrote:
> Common code in NUMA need these two helpers to access/update
> memory hotplug end address. Arm has not support memory hotplug
> yet. So we stub these two helpers in this patch to make NUMA
> common code happy.
> 
> Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> ---
>  xen/include/asm-arm/mm.h | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h
> index 7b5e7b7f69..fc9433165d 100644
> --- a/xen/include/asm-arm/mm.h
> +++ b/xen/include/asm-arm/mm.h
> @@ -362,6 +362,16 @@ void clear_and_clean_page(struct page_info *page);
>  
>  unsigned int arch_get_dma_bitsize(void);
>  
> +static inline void mem_hotplug_update_boundary(paddr_t end)
> +{
> +
> +}
> +
> +static inline paddr_t mem_hotplug_boundary(void)
> +{
> +    return 0;
> +}

Why zero? Could it be INVALID_PADDR ?