Re: [Xen-devel] [PATCH v8 for-4.12 10/17] argo: implement the notify op

[Julien Grall <julien.grall@xxxxxxx>]

Hi,

On 2/6/19 8:55 AM, Christopher Clark wrote:
> +/*
> + * XEN_ARGO_OP_notify
> + *
> + * Asks Xen for information about other rings in the system.
> + *
> + * ent->ring is the xen_argo_addr_t of the ring you want information on.
> + * Uses the same ring matching rules as XEN_ARGO_OP_sendv.
> + *
> + * ent->space_required : if this field is not null then Xen will check
> + * that there is space in the destination ring for this many bytes of payload.
> + * If the ring is too small for the requested space_required, it will set the
> + * XEN_ARGO_RING_EMSGSIZE flag on return.
> + * If sufficient space is available, it will set XEN_ARGO_RING_SUFFICIENT
> + * and CANCEL any pending notification for that ent->ring; otherwise it
> + * will schedule a notification event and the flag will not be set.
> + *
> + * These flags are set by Xen when notify replies:
> + * XEN_ARGO_RING_EXISTS     ring exists
> + * XEN_ARGO_RING_SHARED     ring is registered for wildcard partner
> + * XEN_ARGO_RING_EMPTY      ring is empty
> + * XEN_ARGO_RING_SUFFICIENT sufficient space for space_required is there
> + * XEN_ARGO_RING_EMSGSIZE   space_required is too large for the ring size
> + * XEN_ARGO_RING_EBUSY      too many domains waiting for available space 
> signals
> + *
> + * arg1: XEN_GUEST_HANDLE(xen_argo_ring_data_t) ring_data (may be NULL)
> + * arg2: NULL
NIT: While looking at all the hypercall, I noticed you say NULL here. In 
most of the cases, NULL will be 0 but there are place where it might not 
be. So what is the exact value you expect here?
> + * arg3: 0 (ZERO)
> + * arg4: 0 (ZERO)
NIT: I guess those to will be 0 in an unsigned long value?

> + */
> +#define XEN_ARGO_OP_notify              4
> +
>   #endif
> diff --git a/xen/include/xlat.lst b/xen/include/xlat.lst
> index 0d65f6a..e330f72 100644
> --- a/xen/include/xlat.lst
> +++ b/xen/include/xlat.lst
> @@ -34,6 +34,8 @@
>   !     argo_iov                        argo.h
>   ?     argo_register_ring              argo.h
>   ?     argo_ring                       argo.h
> +?      argo_ring_data                  argo.h
> +?      argo_ring_data_ent              argo.h
>   ?     argo_ring_message_header        argo.h
>   ?     argo_send_addr                  argo.h
>   ?     argo_unregister_ring            argo.h
Cheers,

--
Julien Grall

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