Re: [XEN PATCH v2] xen: move declaration of first_valid_mfn to xen/numa.h

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 18 Dec 2023, Nicola Vetrini wrote:
> Such declaration is moved in order to provide it for Arm and PPC,
> whilst not violating MISRA C:2012 Rule 8.4 in common/page_alloc.c:
> "A compatible declaration shall be visible when an object or
> function with external linkage is defined".
> 
> Signed-off-by: Julien Grall <julien@xxxxxxx>
> Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
> Changes in v2:
> This patch is a rework of a previous one appeared in this series [1], of which
> patches 1 and 2 have been committed already.
> 
> The updated patch was provided by Julien in this thread [2]. I added the 
> commit
> message and the rest of the information.
> 
> [1] 
> https://lore.kernel.org/xen-devel/cover.1702285639.git.nicola.vetrini@xxxxxxxxxxx/T/#mee6def855787d932fe2f10d5648d437dcb6f046c
> [2] 
> https://lore.kernel.org/xen-devel/cover.1702285639.git.nicola.vetrini@xxxxxxxxxxx/T/#m3c5b141b806530b5920bb5e9dd53631195560317
> ---
>  xen/arch/arm/include/asm/numa.h | 6 ------
>  xen/arch/ppc/include/asm/numa.h | 6 ------
>  xen/common/page_alloc.c         | 6 ++++--
>  xen/include/xen/numa.h          | 2 ++
>  4 files changed, 6 insertions(+), 14 deletions(-)
> 
> diff --git a/xen/arch/arm/include/asm/numa.h b/xen/arch/arm/include/asm/numa.h
> index e2bee2bd8223..a2c1da4a82f7 100644
> --- a/xen/arch/arm/include/asm/numa.h
> +++ b/xen/arch/arm/include/asm/numa.h
> @@ -11,12 +11,6 @@ typedef u8 nodeid_t;
>  #define cpu_to_node(cpu) 0
>  #define node_to_cpumask(node)   (cpu_online_map)
>  
> -/*
> - * TODO: make first_valid_mfn static when NUMA is supported on Arm, this
> - * is required because the dummy helpers are using it.
> - */
> -extern mfn_t first_valid_mfn;
> -
>  /* XXX: implement NUMA support */
>  #define node_spanned_pages(nid) (max_page - mfn_x(first_valid_mfn))
>  #define node_start_pfn(nid) (mfn_x(first_valid_mfn))
> diff --git a/xen/arch/ppc/include/asm/numa.h b/xen/arch/ppc/include/asm/numa.h
> index 7fdf66c3da74..204180ad5b98 100644
> --- a/xen/arch/ppc/include/asm/numa.h
> +++ b/xen/arch/ppc/include/asm/numa.h
> @@ -10,12 +10,6 @@ typedef uint8_t nodeid_t;
>  #define cpu_to_node(cpu) 0
>  #define node_to_cpumask(node)   (cpu_online_map)
>  
> -/*
> - * TODO: make first_valid_mfn static when NUMA is supported on PPC, this
> - * is required because the dummy helpers are using it.
> - */
> -extern mfn_t first_valid_mfn;
> -
>  /* XXX: implement NUMA support */
>  #define node_spanned_pages(nid) (max_page - mfn_x(first_valid_mfn))
>  #define node_start_pfn(nid) (mfn_x(first_valid_mfn))
> diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
> index 9b5df74fddab..d874525916ea 100644
> --- a/xen/common/page_alloc.c
> +++ b/xen/common/page_alloc.c
> @@ -255,8 +255,10 @@ static PAGE_LIST_HEAD(page_broken_list);
>   */
>  
>  /*
> - * first_valid_mfn is exported because it is use in ARM specific NUMA
> - * helpers. See comment in arch/arm/include/asm/numa.h.
> + * first_valid_mfn is exported because it is used when !CONFIG_NUMA.
> + *
> + * TODO: Consider if we can conditionally export first_valid_mfn based
> + * on whether NUMA is selected.
>   */
>  mfn_t first_valid_mfn = INVALID_MFN_INITIALIZER;
>  
> diff --git a/xen/include/xen/numa.h b/xen/include/xen/numa.h
> index 287e81ff6666..a10d4b1778a0 100644
> --- a/xen/include/xen/numa.h
> +++ b/xen/include/xen/numa.h
> @@ -108,6 +108,8 @@ extern void numa_set_processor_nodes_parsed(nodeid_t 
> node);
>  
>  #else
>  
> +extern mfn_t first_valid_mfn;
> +
>  static inline nodeid_t mfn_to_nid(mfn_t mfn)
>  {
>      return 0;
> -- 
> 2.34.1
>