5819da83ce
TUNABLE variable (hw.netmap.buf_size) so we can experiment with values different from 2048 which may give better cache performance. - rearrange the memory allocation code so it will be easier to replace it with a different implementation. The current code relies on a single large contiguous chunk of memory obtained through contigmalloc. The new implementation (not committed yet) uses multiple smaller chunks which are easier to fit in a fragmented address space.
269 lines
11 KiB
C
269 lines
11 KiB
C
/*
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* Copyright (C) 2011 Matteo Landi, Luigi Rizzo. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the
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* distribution.
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*
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* 3. Neither the name of the authors nor the names of their contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY MATTEO LANDI AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTEO LANDI OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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* THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* $FreeBSD$
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* $Id: netmap.h 9753 2011-11-28 15:10:43Z luigi $
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*
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* This header contains the definitions of the constants and the
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* structures needed by the ``netmap'' module, both kernel and
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* userspace.
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*/
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#ifndef _NET_NETMAP_H_
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#define _NET_NETMAP_H_
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/*
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* --- Netmap data structures ---
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*
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* The data structures used by netmap are shown below. Those in
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* capital letters are in an mmapp()ed area shared with userspace,
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* while others are private to the kernel.
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* Shared structures do not contain pointers but only relative
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* offsets, so that addressing is portable between kernel and userspace.
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*
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* The 'softc' of each interface is extended with a struct netmap_adapter
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* containing information to support netmap operation. In addition to
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* the fixed fields, it has two pointers to reach the arrays of
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* 'struct netmap_kring' which in turn reaches the various
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* struct netmap_ring, shared with userspace.
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softc
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+----------------+
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| standard fields|
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| if_pspare[0] ----------+
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+----------------+ |
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+----------------+<------+
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|(netmap_adapter)|
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| | netmap_kring
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| tx_rings *--------------------------------->+-------------+
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| | netmap_kring | ring *---------> ...
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| rx_rings *---------->+--------------+ | nr_hwcur |
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+----------------+ | ring *-------+ | nr_hwavail |
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| nr_hwcur | | | selinfo |
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| nr_hwavail | | +-------------+
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| selinfo | | | ... |
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+--------------+ | (na_num_rings+1 entries)
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| .... | | | |
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(na_num_rings+1 entries) +-------------+
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| | |
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+--------------+ |
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| NETMAP_RING
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+---->+-------------+
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/ | cur |
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NETMAP_IF (nifp, one per file desc.) / | avail |
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+---------------+ / | buf_ofs |
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| ni_num_queues | / +=============+
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| | / | buf_idx | slot[0]
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| | / | len, flags |
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| | / +-------------+
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+===============+ / | buf_idx | slot[1]
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| txring_ofs[0] | (rel.to nifp)--' | len, flags |
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| txring_ofs[1] | +-------------+
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(num_rings+1 entries) (nr_num_slots entries)
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| txring_ofs[n] | | buf_idx | slot[n-1]
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+---------------+ | len, flags |
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| rxring_ofs[0] | +-------------+
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| rxring_ofs[1] |
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(num_rings+1 entries)
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| txring_ofs[n] |
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+---------------+
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* The NETMAP_RING is the shadow ring that mirrors the NIC rings.
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* Each slot has the index of a buffer, its length and some flags.
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* In user space, the buffer address is computed as
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* (char *)ring + buf_ofs + index*MAX_BUF_SIZE
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* In the kernel, buffers do not necessarily need to be contiguous,
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* and the virtual and physical addresses are derived through
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* a lookup table. When userspace wants to use a different buffer
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* in a location, it must set the NS_BUF_CHANGED flag to make
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* sure that the kernel recomputes updates the hardware ring and
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* other fields (bus_dmamap, etc.) as needed.
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*
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* Normally the driver is not requested to report the result of
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* transmissions (this can dramatically speed up operation).
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* However the user may request to report completion by setting
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* NS_REPORT.
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*/
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struct netmap_slot {
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uint32_t buf_idx; /* buffer index */
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uint16_t len; /* packet length, to be copied to/from the hw ring */
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uint16_t flags; /* buf changed, etc. */
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#define NS_BUF_CHANGED 0x0001 /* must resync the map, buffer changed */
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#define NS_REPORT 0x0002 /* ask the hardware to report results
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* e.g. by generating an interrupt
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*/
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};
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/*
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* Netmap representation of a TX or RX ring (also known as "queue").
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* This is a queue implemented as a fixed-size circular array.
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* At the software level, two fields are important: avail and cur.
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*
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* In TX rings:
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* avail indicates the number of slots available for transmission.
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* It is decremented by the application when it appends a
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* packet, and set to nr_hwavail (see below) on a
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* NIOCTXSYNC to reflect the actual state of the queue
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* (keeping track of completed transmissions).
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* cur indicates the empty slot to use for the next packet
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* to send (i.e. the "tail" of the queue).
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* It is incremented by the application.
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*
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* The kernel side of netmap uses two additional fields in its own
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* private ring structure, netmap_kring:
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* nr_hwcur is a copy of nr_cur on an NIOCTXSYNC.
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* nr_hwavail is the number of slots known as available by the
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* hardware. It is updated on an INTR (inc by the
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* number of packets sent) and on a NIOCTXSYNC
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* (decrease by nr_cur - nr_hwcur)
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* A special case, nr_hwavail is -1 if the transmit
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* side is idle (no pending transmits).
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*
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* In RX rings:
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* avail is the number of packets available (possibly 0).
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* It is decremented by the software when it consumes
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* a packet, and set to nr_hwavail on a NIOCRXSYNC
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* cur indicates the first slot that contains a packet
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* (the "head" of the queue).
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* It is incremented by the software when it consumes
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* a packet.
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*
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* The kernel side of netmap uses two additional fields in the kring:
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* nr_hwcur is a copy of nr_cur on an NIOCRXSYNC
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* nr_hwavail is the number of packets available. It is updated
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* on INTR (inc by the number of new packets arrived)
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* and on NIOCRXSYNC (decreased by nr_cur - nr_hwcur).
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*
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* DATA OWNERSHIP/LOCKING:
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* The netmap_ring is owned by the user program and it is only
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* accessed or modified in the upper half of the kernel during
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* a system call.
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*
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* The netmap_kring is only modified by the upper half of the kernel.
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*/
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struct netmap_ring {
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/*
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* nr_buf_base_ofs is meant to be used through macros.
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* It contains the offset of the buffer region from this
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* descriptor.
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*/
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const ssize_t buf_ofs;
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const uint32_t num_slots; /* number of slots in the ring. */
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uint32_t avail; /* number of usable slots */
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uint32_t cur; /* 'current' r/w position */
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const uint16_t nr_buf_size;
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uint16_t flags;
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#define NR_TIMESTAMP 0x0002 /* set timestamp on *sync() */
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struct timeval ts; /* time of last *sync() */
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/* the slots follow. This struct has variable size */
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struct netmap_slot slot[0]; /* array of slots. */
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};
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/*
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* Netmap representation of an interface and its queue(s).
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* There is one netmap_if for each file descriptor on which we want
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* to select/poll. We assume that on each interface has the same number
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* of receive and transmit queues.
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* select/poll operates on one or all pairs depending on the value of
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* nmr_queueid passed on the ioctl.
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*/
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struct netmap_if {
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char ni_name[IFNAMSIZ]; /* name of the interface. */
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const u_int ni_version; /* API version, currently unused */
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const u_int ni_num_queues; /* number of queue pairs (TX/RX). */
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const u_int ni_rx_queues; /* if zero, use ni_num_queues */
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/*
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* the following array contains the offset of the
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* each netmap ring from this structure. The first num_queues+1
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* refer to the tx rings, the next n+1 refer to the rx rings.
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* The area is filled up by the kernel on NIOCREG,
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* and then only read by userspace code.
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* entries 0..ni_num_queues-1 indicate the hardware queues,
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* entry ni_num_queues is the queue from/to the stack.
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*/
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const ssize_t ring_ofs[0];
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};
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#ifndef IFCAP_NETMAP /* this should go in net/if.h */
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#define IFCAP_NETMAP 0x100000
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#endif
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#ifndef NIOCREGIF
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/*
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* ioctl names and related fields
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*
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* NIOCGINFO takes a struct ifreq, the interface name is the input,
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* the outputs are number of queues and number of descriptor
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* for each queue (useful to set number of threads etc.).
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*
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* NIOCREGIF takes an interface name within a struct ifreq,
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* and activates netmap mode on the interface (if possible).
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*
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* NIOCUNREGIF unregisters the interface associated to the fd.
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*
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* NIOCTXSYNC, NIOCRXSYNC synchronize tx or rx queues,
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* whose identity is set in NIOCREGIF through nr_ringid
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*/
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/*
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* struct nmreq overlays a struct ifreq
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*/
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struct nmreq {
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char nr_name[IFNAMSIZ];
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uint32_t nr_version; /* API version (unused) */
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uint32_t nr_offset; /* nifp offset in the shared region */
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uint32_t nr_memsize; /* size of the shared region */
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uint32_t nr_numslots; /* descriptors per queue */
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uint16_t nr_numrings;
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uint16_t nr_ringid; /* ring(s) we care about */
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#define NETMAP_HW_RING 0x4000 /* low bits indicate one hw ring */
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#define NETMAP_SW_RING 0x2000 /* we process the sw ring */
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#define NETMAP_NO_TX_POLL 0x1000 /* no gratuitous txsync on poll */
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#define NETMAP_RING_MASK 0xfff /* the ring number */
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};
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#define NIOCGINFO _IOWR('i', 145, struct nmreq) /* return IF info */
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#define NIOCREGIF _IOWR('i', 146, struct nmreq) /* interface register */
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#define NIOCUNREGIF _IO('i', 147) /* interface unregister */
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#define NIOCTXSYNC _IO('i', 148) /* sync tx queues */
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#define NIOCRXSYNC _IO('i', 149) /* sync rx queues */
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#endif /* !NIOCREGIF */
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#endif /* _NET_NETMAP_H_ */
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