Re: [PATCH v2 1/2] numa: Set default distance map if needed

[Andrew Jones]

On Tue, Oct 12, 2021 at 02:36:02PM +0800, Gavin Shan wrote:
> The following option is used to specify the distance map. It's
> possible the option isn't provided by user. In this case, the
> distance map isn't populated and exposed to platform. On the
> other hand, the empty NUMA node, where no memory resides, is
> allowed on ARM64 virt platform. For these empty NUMA nodes,
> their corresponding device-tree nodes aren't populated, but
> their NUMA IDs should be included in the "/distance-map"
> device-tree node, so that kernel can probe them properly if
> device-tree is used.
> 
>   -numa,dist,src=<numa_id>,dst=<numa_id>,val=<distance>
> 
> So when user doesn't specify distance map, we need to generate
> the default distance map, where the local and remote distances
> are 10 and 20 separately. However, this is going to change the
> hardware description of the guest in this particular scenario.
> It's fine as the guest should be tolerant to ignore the distance
> map completely or parse it properly by following the device-tree
> specification.
> 
> This introduces an extra parameter to the exiting function
> complete_init_numa_distance() to generate the default distance
> map when no node pair distances are provided by user.
> 
> Signed-off-by: Gavin Shan <gshan@redhat.com>
> ---
>  hw/core/numa.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
>

Reviewed-by: Andrew Jones <drjones@redhat.com>