Re: [Xen-devel] [PATCH 1/5] xen: improve changes to xen_add_to_physmap

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 06.08.12 at 16:12, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
wrote:
> This is an incremental patch on top of
> c0bc926083b5987a3e9944eec2c12ad0580100e2: in order to retain binary
> compatibility, it is better to introduce foreign_domid as part of a
> union containing both size and foreign_domid.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> ---
>  xen/include/public/memory.h |   11 +++++++----
>  1 files changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
> index b2adfbe..b0af2fd 100644
> --- a/xen/include/public/memory.h
> +++ b/xen/include/public/memory.h
> @@ -208,8 +208,12 @@ struct xen_add_to_physmap {
>      /* Which domain to change the mapping for. */
>      domid_t domid;
>  
> -    /* Number of pages to go through for gmfn_range */
> -    uint16_t    size;
> +    union {
> +        /* Number of pages to go through for gmfn_range */
> +        uint16_t    size;
> +        /* IFF gmfn_foreign */
> +        domid_t foreign_domid;
> +    };

But you're clear that this isn't standard C, and hence can't go
in this way?

Jan

>      /* Source mapping space. */
>  #define XENMAPSPACE_shared_info  0 /* shared info page */
> @@ -217,8 +221,7 @@ struct xen_add_to_physmap {
>  #define XENMAPSPACE_gmfn         2 /* GMFN */
>  #define XENMAPSPACE_gmfn_range   3 /* GMFN range */
>  #define XENMAPSPACE_gmfn_foreign 4 /* GMFN from another guest */
> -    uint16_t space;
> -    domid_t foreign_domid; /* IFF gmfn_foreign */
> +    unsigned int space;
>  
>  #define XENMAPIDX_grant_table_status 0x80000000
>  
> -- 
> 1.7.2.5
> 
> 
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> http://lists.xen.org/xen-devel 




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