263 lines
9.7 KiB
C
263 lines
9.7 KiB
C
/******************************************************************************
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* netif.h
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*
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* Unified network-device I/O interface for Xen guest OSes.
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*
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* Copyright (c) 2003-2004, Keir Fraser
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*/
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#ifndef __XEN_PUBLIC_IO_NETIF_H__
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#define __XEN_PUBLIC_IO_NETIF_H__
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#include <xen/interface/io/ring.h>
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#include <xen/interface/grant_table.h>
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/*
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* Older implementation of Xen network frontend / backend has an
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* implicit dependency on the MAX_SKB_FRAGS as the maximum number of
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* ring slots a skb can use. Netfront / netback may not work as
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* expected when frontend and backend have different MAX_SKB_FRAGS.
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*
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* A better approach is to add mechanism for netfront / netback to
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* negotiate this value. However we cannot fix all possible
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* frontends, so we need to define a value which states the minimum
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* slots backend must support.
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*
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* The minimum value derives from older Linux kernel's MAX_SKB_FRAGS
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* (18), which is proved to work with most frontends. Any new backend
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* which doesn't negotiate with frontend should expect frontend to
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* send a valid packet using slots up to this value.
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*/
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#define XEN_NETIF_NR_SLOTS_MIN 18
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/*
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* Notifications after enqueuing any type of message should be conditional on
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* the appropriate req_event or rsp_event field in the shared ring.
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* If the client sends notification for rx requests then it should specify
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* feature 'feature-rx-notify' via xenbus. Otherwise the backend will assume
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* that it cannot safely queue packets (as it may not be kicked to send them).
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*/
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/*
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* "feature-split-event-channels" is introduced to separate guest TX
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* and RX notificaion. Backend either doesn't support this feature or
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* advertise it via xenstore as 0 (disabled) or 1 (enabled).
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*
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* To make use of this feature, frontend should allocate two event
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* channels for TX and RX, advertise them to backend as
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* "event-channel-tx" and "event-channel-rx" respectively. If frontend
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* doesn't want to use this feature, it just writes "event-channel"
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* node as before.
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*/
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/*
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* Multiple transmit and receive queues:
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* If supported, the backend will write the key "multi-queue-max-queues" to
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* the directory for that vif, and set its value to the maximum supported
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* number of queues.
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* Frontends that are aware of this feature and wish to use it can write the
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* key "multi-queue-num-queues", set to the number they wish to use, which
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* must be greater than zero, and no more than the value reported by the backend
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* in "multi-queue-max-queues".
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*
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* Queues replicate the shared rings and event channels.
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* "feature-split-event-channels" may optionally be used when using
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* multiple queues, but is not mandatory.
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*
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* Each queue consists of one shared ring pair, i.e. there must be the same
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* number of tx and rx rings.
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*
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* For frontends requesting just one queue, the usual event-channel and
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* ring-ref keys are written as before, simplifying the backend processing
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* to avoid distinguishing between a frontend that doesn't understand the
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* multi-queue feature, and one that does, but requested only one queue.
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*
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* Frontends requesting two or more queues must not write the toplevel
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* event-channel (or event-channel-{tx,rx}) and {tx,rx}-ring-ref keys,
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* instead writing those keys under sub-keys having the name "queue-N" where
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* N is the integer ID of the queue for which those keys belong. Queues
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* are indexed from zero. For example, a frontend with two queues and split
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* event channels must write the following set of queue-related keys:
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*
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* /local/domain/1/device/vif/0/multi-queue-num-queues = "2"
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* /local/domain/1/device/vif/0/queue-0 = ""
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* /local/domain/1/device/vif/0/queue-0/tx-ring-ref = "<ring-ref-tx0>"
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* /local/domain/1/device/vif/0/queue-0/rx-ring-ref = "<ring-ref-rx0>"
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* /local/domain/1/device/vif/0/queue-0/event-channel-tx = "<evtchn-tx0>"
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* /local/domain/1/device/vif/0/queue-0/event-channel-rx = "<evtchn-rx0>"
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* /local/domain/1/device/vif/0/queue-1 = ""
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* /local/domain/1/device/vif/0/queue-1/tx-ring-ref = "<ring-ref-tx1>"
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* /local/domain/1/device/vif/0/queue-1/rx-ring-ref = "<ring-ref-rx1"
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* /local/domain/1/device/vif/0/queue-1/event-channel-tx = "<evtchn-tx1>"
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* /local/domain/1/device/vif/0/queue-1/event-channel-rx = "<evtchn-rx1>"
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*
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* If there is any inconsistency in the XenStore data, the backend may
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* choose not to connect any queues, instead treating the request as an
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* error. This includes scenarios where more (or fewer) queues were
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* requested than the frontend provided details for.
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*
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* Mapping of packets to queues is considered to be a function of the
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* transmitting system (backend or frontend) and is not negotiated
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* between the two. Guests are free to transmit packets on any queue
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* they choose, provided it has been set up correctly. Guests must be
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* prepared to receive packets on any queue they have requested be set up.
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*/
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/*
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* "feature-no-csum-offload" should be used to turn IPv4 TCP/UDP checksum
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* offload off or on. If it is missing then the feature is assumed to be on.
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* "feature-ipv6-csum-offload" should be used to turn IPv6 TCP/UDP checksum
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* offload on or off. If it is missing then the feature is assumed to be off.
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*/
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/*
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* "feature-gso-tcpv4" and "feature-gso-tcpv6" advertise the capability to
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* handle large TCP packets (in IPv4 or IPv6 form respectively). Neither
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* frontends nor backends are assumed to be capable unless the flags are
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* present.
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*/
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/*
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* This is the 'wire' format for packets:
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* Request 1: xen_netif_tx_request -- XEN_NETTXF_* (any flags)
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* [Request 2: xen_netif_extra_info] (only if request 1 has XEN_NETTXF_extra_info)
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* [Request 3: xen_netif_extra_info] (only if request 2 has XEN_NETIF_EXTRA_MORE)
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* Request 4: xen_netif_tx_request -- XEN_NETTXF_more_data
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* Request 5: xen_netif_tx_request -- XEN_NETTXF_more_data
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* ...
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* Request N: xen_netif_tx_request -- 0
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*/
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/* Protocol checksum field is blank in the packet (hardware offload)? */
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#define _XEN_NETTXF_csum_blank (0)
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#define XEN_NETTXF_csum_blank (1U<<_XEN_NETTXF_csum_blank)
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/* Packet data has been validated against protocol checksum. */
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#define _XEN_NETTXF_data_validated (1)
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#define XEN_NETTXF_data_validated (1U<<_XEN_NETTXF_data_validated)
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/* Packet continues in the next request descriptor. */
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#define _XEN_NETTXF_more_data (2)
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#define XEN_NETTXF_more_data (1U<<_XEN_NETTXF_more_data)
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/* Packet to be followed by extra descriptor(s). */
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#define _XEN_NETTXF_extra_info (3)
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#define XEN_NETTXF_extra_info (1U<<_XEN_NETTXF_extra_info)
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#define XEN_NETIF_MAX_TX_SIZE 0xFFFF
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struct xen_netif_tx_request {
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grant_ref_t gref; /* Reference to buffer page */
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uint16_t offset; /* Offset within buffer page */
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uint16_t flags; /* XEN_NETTXF_* */
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uint16_t id; /* Echoed in response message. */
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uint16_t size; /* Packet size in bytes. */
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};
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/* Types of xen_netif_extra_info descriptors. */
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#define XEN_NETIF_EXTRA_TYPE_NONE (0) /* Never used - invalid */
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#define XEN_NETIF_EXTRA_TYPE_GSO (1) /* u.gso */
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#define XEN_NETIF_EXTRA_TYPE_MAX (2)
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/* xen_netif_extra_info flags. */
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#define _XEN_NETIF_EXTRA_FLAG_MORE (0)
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#define XEN_NETIF_EXTRA_FLAG_MORE (1U<<_XEN_NETIF_EXTRA_FLAG_MORE)
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/* GSO types */
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#define XEN_NETIF_GSO_TYPE_NONE (0)
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#define XEN_NETIF_GSO_TYPE_TCPV4 (1)
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#define XEN_NETIF_GSO_TYPE_TCPV6 (2)
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/*
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* This structure needs to fit within both netif_tx_request and
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* netif_rx_response for compatibility.
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*/
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struct xen_netif_extra_info {
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uint8_t type; /* XEN_NETIF_EXTRA_TYPE_* */
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uint8_t flags; /* XEN_NETIF_EXTRA_FLAG_* */
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union {
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struct {
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/*
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* Maximum payload size of each segment. For
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* example, for TCP this is just the path MSS.
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*/
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uint16_t size;
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/*
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* GSO type. This determines the protocol of
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* the packet and any extra features required
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* to segment the packet properly.
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*/
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uint8_t type; /* XEN_NETIF_GSO_TYPE_* */
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/* Future expansion. */
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uint8_t pad;
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/*
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* GSO features. This specifies any extra GSO
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* features required to process this packet,
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* such as ECN support for TCPv4.
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*/
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uint16_t features; /* XEN_NETIF_GSO_FEAT_* */
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} gso;
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uint16_t pad[3];
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} u;
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};
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struct xen_netif_tx_response {
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uint16_t id;
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int16_t status; /* XEN_NETIF_RSP_* */
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};
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struct xen_netif_rx_request {
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uint16_t id; /* Echoed in response message. */
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grant_ref_t gref; /* Reference to incoming granted frame */
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};
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/* Packet data has been validated against protocol checksum. */
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#define _XEN_NETRXF_data_validated (0)
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#define XEN_NETRXF_data_validated (1U<<_XEN_NETRXF_data_validated)
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/* Protocol checksum field is blank in the packet (hardware offload)? */
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#define _XEN_NETRXF_csum_blank (1)
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#define XEN_NETRXF_csum_blank (1U<<_XEN_NETRXF_csum_blank)
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/* Packet continues in the next request descriptor. */
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#define _XEN_NETRXF_more_data (2)
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#define XEN_NETRXF_more_data (1U<<_XEN_NETRXF_more_data)
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/* Packet to be followed by extra descriptor(s). */
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#define _XEN_NETRXF_extra_info (3)
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#define XEN_NETRXF_extra_info (1U<<_XEN_NETRXF_extra_info)
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/* GSO Prefix descriptor. */
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#define _XEN_NETRXF_gso_prefix (4)
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#define XEN_NETRXF_gso_prefix (1U<<_XEN_NETRXF_gso_prefix)
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struct xen_netif_rx_response {
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uint16_t id;
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uint16_t offset; /* Offset in page of start of received packet */
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uint16_t flags; /* XEN_NETRXF_* */
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int16_t status; /* -ve: BLKIF_RSP_* ; +ve: Rx'ed pkt size. */
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};
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/*
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* Generate netif ring structures and types.
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*/
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DEFINE_RING_TYPES(xen_netif_tx,
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struct xen_netif_tx_request,
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struct xen_netif_tx_response);
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DEFINE_RING_TYPES(xen_netif_rx,
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struct xen_netif_rx_request,
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struct xen_netif_rx_response);
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#define XEN_NETIF_RSP_DROPPED -2
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#define XEN_NETIF_RSP_ERROR -1
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#define XEN_NETIF_RSP_OKAY 0
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/* No response: used for auxiliary requests (e.g., xen_netif_extra_info). */
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#define XEN_NETIF_RSP_NULL 1
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#endif
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