Re: [XEN RFC PATCH 32/40] xen/x86: make acpi_scan_nodes to be neutral

[Julien Grall <julien@xxxxxxx>]

Hi Wei,

On 11/08/2021 11:24, Wei Chen wrote:
> The code in acpi_scan_nodes can be reused for device tree based
> NUMA. So we rename acpi_scan_nodes to numa_scan_nodes for a neutral
> function name. As acpi_numa variable is available in ACPU based NUMA
> system only, we use CONFIG_ACPI_NUMA to protect it.
>
> Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> ---
>   xen/arch/x86/srat.c        | 4 +++-
>   xen/common/numa.c          | 2 +-
>   xen/include/asm-x86/acpi.h | 2 +-
>   3 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/xen/arch/x86/srat.c b/xen/arch/x86/srat.c
> index dcebc7adec..3d4d90a622 100644
> --- a/xen/arch/x86/srat.c
> +++ b/xen/arch/x86/srat.c
> @@ -362,7 +362,7 @@ void __init srat_parse_regions(u64 addr)
>   }
>   
>   /* Use the information discovered above to actually set up the nodes. */
> -int __init acpi_scan_nodes(u64 start, u64 end)
> +int __init numa_scan_nodes(u64 start, u64 end)
>   {
>         int i;
>         nodemask_t all_nodes_parsed;
> @@ -371,8 +371,10 @@ int __init acpi_scan_nodes(u64 start, u64 end)
>         for (i = 0; i < MAX_NUMNODES; i++)
>                 cutoff_node(i, start, end);
>   
> +#ifdef CONFIG_ACPI_NUMA
>         if (acpi_numa <= 0)
>                 return -1;
> +#endif
Looking at the follow-up patches, I find a bit odd that there is a check 
for ACPI but there is none added for DT. Can you explain why?
However, I think this check is going to impair the work to support both 
ACPI and DT on Arm because acpi_numa would end up to be 0 so you would 
bail out here.
With that in mind, I think this check needs to either go away or replace 
by something there is firmware agnostic.
Cheers,

--
Julien Grall