FreeBSD/Linux Kernel Cross Reference
sys/dev/virtio/balloon/virtio_balloon.h

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * This header is BSD licensed so anyone can use the definitions to implement
      * compatible drivers/servers.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of IBM nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    
    #ifndef _VIRTIO_BALLOON_H
    #define _VIRTIO_BALLOON_H
    
    /* Feature bits. */
    #define VIRTIO_BALLOON_F_MUST_TELL_HOST 0x1 /* Tell before reclaiming pages */
    #define VIRTIO_BALLOON_F_STATS_VQ       0x2 /* Memory stats virtqueue */
    #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 0x4 /* Deflate balloon on OOM */
    
    /* Size of a PFN in the balloon interface. */
    #define VIRTIO_BALLOON_PFN_SHIFT 12
    
    struct virtio_balloon_config {
            /* Number of pages host wants Guest to give up. */
            uint32_t num_pages;
    
            /* Number of pages we've actually got in balloon. */
            uint32_t actual;
    };
    
    #define VIRTIO_BALLOON_S_SWAP_IN  0   /* Amount of memory swapped in */
    #define VIRTIO_BALLOON_S_SWAP_OUT 1   /* Amount of memory swapped out */
    #define VIRTIO_BALLOON_S_MAJFLT   2   /* Number of major faults */
    #define VIRTIO_BALLOON_S_MINFLT   3   /* Number of minor faults */
    #define VIRTIO_BALLOON_S_MEMFREE  4   /* Total amount of free memory */
    #define VIRTIO_BALLOON_S_MEMTOT   5   /* Total amount of memory */
    #define VIRTIO_BALLOON_S_AVAIL    6   /* Available memory as in /proc */
    #define VIRTIO_BALLOON_S_CACHES   7   /* Disk caches */
    #define VIRTIO_BALLOON_S_NR       8
    
    /*
     * Memory statistics structure.
     * Driver fills an array of these structures and passes to device.
     *
     * NOTE: fields are laid out in a way that would make compiler add padding
     * between and after fields, so we have to use compiler-specific attributes to
     * pack it, to disable this padding. This also often causes compiler to
     * generate suboptimal code.
     *
     * We maintain this statistics structure format for backwards compatibility,
     * but don't follow this example.
     *
     * If implementing a similar structure, do something like the below instead:
     *     struct virtio_balloon_stat {
     *         __virtio16 tag;
     *         __u8 reserved[6];
     *         __virtio64 val;
     *     };
     *
     * In other words, add explicit reserved fields to align field and
     * structure boundaries at field size, avoiding compiler padding
     * without the packed attribute.
     */
    struct virtio_balloon_stat {
            uint16_t tag;
            uint64_t val;
    } __packed;
    
    #endif /* _VIRTIO_BALLOON_H */

Cache object: a73b294425268a0c39ee5246e67da959