[Xen-devel] Is: ARM maintainers advice ..Was:Re: [PATCH v5 11/28] xsplice: Implement support for applying/reverting/replacing patches.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 10.04.16 at 21:47, <konrad.wilk@xxxxxxxxxx> wrote:
> That allows the size and offsets to be the same. I checked under ARM32
> builds:
> 
> 
> struct xsplice_patch_func_internal {
>     const char  *              name;                 /*     0     4 */
>     uint32_t                   _pad0;                /*     4     4 */
>     void *                     new_addr;             /*     8     4 */
>     uint32_t                   _pad1;                /*    12     4 */
>     void *                     old_addr;             /*    16     4 */
>     uint32_t                   _pad2;                /*    20     4 */
>     uint32_t                   new_size;             /*    24     4 */
>     uint32_t                   old_size;             /*    28     4 */
>     uint8_t                    version;              /*    32     1 */
>     union {
>         uint8_t            pad[31];              /*          31 */
>     } u;                                             /*    33    31 */
>     /* --- cacheline 1 boundary (64 bytes) --- */
> 
>     /* size: 64, cachelines: 1, members: 10 */
> };
> 
> So it all looks correct. (and I can cast the old_addr to uint8_t).
> Naturally we can expand the pad[] to hold whatever is needed
> when implementing xSplice under ARM

I still don't get: Why is it so important for this structure to have
the same size and layout across architectures?

Jan


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