Re: [Xen-devel] [PATCH] xen/evtchn: rearrange fields

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 24.03.14 at 15:10, <dgdegra@xxxxxxxxxxxxx> wrote:
> --- a/xen/include/xen/sched.h
> +++ b/xen/include/xen/sched.h
> @@ -78,7 +78,8 @@ struct evtchn
>  #define ECS_VIRQ         5 /* Channel is bound to a virtual IRQ line.       
>  */
>  #define ECS_IPI          6 /* Channel is bound to a virtual IPI line.       
>  */
>      u8  state;             /* ECS_* */
> -    u8  xen_consumer;      /* Consumer in Xen, if any? (0 = send to guest) */
> +    u8  xen_consumer:7;    /* Consumer in Xen, if any? (0 = send to guest) */
> +    u8  pending:1;

While the change is fine this way from a high level perspective, I'd
really like this to be connected up properly: #define the number of
bits you need here (3 or 4), and use it both here and in the
definition of xen_consumers[] (which then would become an array
of either 7 or 15 elements, depending on the number of bits you
pick). That way there's going to be a single place controlling all
aspects, and hence a single place needing change (and attention)
when eventually needing to grow the count of Xen consumers.

Jan


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