Re: [Xen-devel] [PATCH 7/7] xen/arm: get the number of cpus from device tree

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2012-11-13 at 15:42 +0000, Stefano Stabellini wrote:
> diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
> index 3d1f0f4..5b6dab9 100644
> --- a/xen/common/device_tree.c
> +++ b/xen/common/device_tree.c
> @@ -153,6 +153,25 @@ const char *device_tree_bootargs(const void *fdt)
>      return prop->data;
>  }
>  
> +int device_tree_cpus(const void *fdt)
> +{
> +    int node = 0, depth = 1;
> +    int cpus = 0;
> +
> +    node = fdt_path_offset(fdt, "/cpus/cpu");
> +    if ( node < 0 )
> +        return 1; /* we have at least one cpu */
> +
> +    while ( node >= 0 && depth >= 0 ) {
> +        if ( strncmp(fdt_get_name(fdt, node, NULL), "cpu", 3) )
> +            continue;
> +        node = fdt_next_node(fdt, node, &depth);
> +        cpus++;

Do we not need to track the largest <n> for each cpu@<n> which we see,
in order to handle systems with e.g. CPUs 0, 1, 4 & 5?

There are some helpers in device_tree.c to walk over trees like this,
are none of them suitable?



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