Re: [PATCH] getvcpuinfo additional information

["Daniel P. Berrange" <berrange@redhat.com>]

On Tue, Nov 07, 2006 at 04:56:53PM -0500, Ben Thomas wrote:
> On a number of instances, it has proved quite useful to be able to
> easily examine more of the VCPU state. Specifically, the information
> contained in the runstate structure.  This patch extends the
> returned information to contain the entire runstate structure.
> A simple usage example is a dom0 user-mode program that can dump all
> of the times for each VCPU (eg, running, blocked, runnable).

[snip]

> Index: xen-unstable.hg/xen/include/public/domctl.h
> ===================================================================
> --- xen-unstable.hg.orig/xen/include/public/domctl.h    2006-11-06 17:12:03.000000000 -0500
> +++ xen-unstable.hg/xen/include/public/domctl.h 2006-11-06 17:12:08.000000000 -0500
> @@ -15,6 +15,7 @@
> #endif
>
>  #include "xen.h"
> +#include "vcpu.h"
>
>  #define XEN_DOMCTL_INTERFACE_VERSION 0x00000004
>
> @@ -239,8 +240,8 @@
>      uint8_t  online;                  /* currently online (not hotplugged)? */
>      uint8_t  blocked;                 /* blocked waiting for an event? */
>      uint8_t  running;                 /* currently scheduled on its CPU? */
> -    uint64_t cpu_time;                /* total cpu time consumed (ns) */
>      uint32_t cpu;                     /* current mapping   */
> +    vcpu_runstate_info_t runstate;    /* VCPU runstate info (see vcpu.h) */
>  };
>  typedef struct xen_domctl_getvcpuinfo xen_domctl_getvcpuinfo_t;
>  DEFINE_XEN_GUEST_HANDLE(xen_domctl_getvcpuinfo_t);

While I like the improved information reporting this change gives us, this is
breaking the HV <-> Dom0  management API...yet again. At very least the 
XEN_DOMCTL_INTERFACE_VERSION version should be incremented, but personally
I'd like to see API & ABI stability maintained by leaving the existing
hypercall alone & adding a new hypercall which deals with extra data.

Regards,
Dan.
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