Re: [PATCH] RFC: Use memops for mem paging, sharing, and access, instead of domctls

[Olaf Hering <olaf@aepfle.de>]

On Wed, Jan 11, Andres Lagar-Cavilla wrote:

> +++ b/xen/include/public/domctl.h

> +/* Use for teardown/setup of helper<->hypervisor interface for paging, 
> + * access and sharing.*/
>  struct xen_domctl_mem_event_op {
>      uint32_t       op;           /* XEN_DOMCTL_MEM_EVENT_OP_*_* */
>      uint32_t       mode;         /* XEN_DOMCTL_MEM_EVENT_OP_* */
>  
> -    union {
> -        /* OP_ENABLE IN:  Virtual address of shared page */
> -        uint64_aligned_t shared_addr;  
> -        /* PAGING_PREP IN: buffer to immediately fill page in */
> -        uint64_aligned_t buffer;
> -    } u;
> +    uint64_aligned_t shared_addr;  /* IN:  Virtual address of shared page */
>      uint64_aligned_t ring_addr;    /* IN:  Virtual address of ring page */
>  
> -    /* Other OPs */
> -    uint64_aligned_t gfn;          /* IN:  gfn of page being operated on */
> +    /* For binary backwards compatibility */
> +    uint64_aligned_t pad;
>  };

Assuming this struct is routed through libxc, and libxc gets a new
SONAME for every release, doesnt this mean that every old binary has to
be recompiled anyway for the new release?
If so, the padding is not needed.

Olaf