[Qemu-discuss] virtio virt-queue and virt-ring

[Yaodong Yang]

Inside file ./hw/virtio/virtio.c, The following structs are defined. I understood that for each virtual disk, there is a corresponding queue and this queue is implemented by a ring. My questions is what is the meaning of each element inside struct VRing?

Thanks a lot!

typedef struct VRing

{

    unsigned int num;

    hwaddr desc;

    hwaddr avail;

    hwaddr used;

} VRing;

struct VirtQueue

{

    VRing vring;

    hwaddr pa;

    uint16_t last_avail_idx;

    /* Last used index value we have signalled on */

    uint16_t signalled_used;

    /* Last used index value we have signalled on */

    bool signalled_used_valid;

    /* Notification enabled? */

    bool notification;

    uint16_t queue_index;

    int inuse;

    uint16_t vector;

    void (*handle_output)(VirtIODevice *vdev, VirtQueue *vq);

    VirtIODevice *vdev;

    EventNotifier guest_notifier;

    EventNotifier host_notifier;

};