Re: [Xen-devel] [PATCH v2] xen/x86: add a way to obtain the needed number of memory map entries

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 06.12.16 at 14:47, <JGross@xxxxxxxx> wrote:
> Today there is no way for a domain to obtain the number of entries of
> the machine memory map returned by XENMEM_machine_memory_map hypercall.
> 
> Modify the interface to return just the needed number of map entries
> in case the buffer was specified as NULL.
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

albeit I'd like to have at least one more REST maintainer's agreement
that ...

> --- a/xen/include/public/memory.h
> +++ b/xen/include/public/memory.h
> @@ -339,6 +339,8 @@ DEFINE_XEN_GUEST_HANDLE(xen_memory_map_t);
>  /*
>   * Returns the real physical memory map. Passes the same structure as
>   * XENMEM_memory_map.
> + * Specifying buffer as NULL will return the number of entries required
> + * to store the complete memory map.
>   * arg == addr of xen_memory_map_t.
>   */
>  #define XENMEM_machine_memory_map   10

... this slight behavioral change is fine to make.

Jan


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