二十四、V4L2框架主要结构体分析和虚拟摄像头驱动编写

一、V4L2框架主要结构体分析

V4L2（video for linux version 2），是内核中视频设备的驱动框架，为上层访问视频设备提供统一接口。

V4L2整体框架如下图：

图中主要包括两层和三个结构体：

两层是：

1. v4l2驱动核心层：包含video_device和v4l2_device的分配、设置和注册

2. v4l2下层接口层：具体的底层传感器驱动，现在的摄像头可能支持硬件解码，这就需要在摄像头驱动下面提供解码器IC驱动

三个结构体是：

1. v4l2_device：

struct v4l2_device {
    /* dev->driver_data points to this struct.
       Note: dev might be NULL if there is no parent device
       as is the case with e.g. ISA devices. */
    struct device *dev;
    /* used to keep track of the registered subdevs */
    struct list_head subdevs;
    /* lock this struct; can be used by the driver as well if this
       struct is embedded into a larger struct. */
    spinlock_t lock;
    /* unique device name, by default the driver name + bus ID */
    char name[V4L2_DEVICE_NAME_SIZE];
    /* notify callback called by some sub-devices. */
    void (*notify)(struct v4l2_subdev *sd,
            unsigned int notification, void *arg);
    /* The control handler. May be NULL. */
    struct v4l2_ctrl_handler *ctrl_handler;
    /* Device's priority state */
    struct v4l2_prio_state prio;
    /* BKL replacement mutex. Temporary solution only. */
    struct mutex ioctl_lock;
    /* Keep track of the references to this struct. */
    struct kref ref;
    /* Release function that is called when the ref count goes to 0. */
    void (*release)(struct v4l2_device *v4l2_dev);
};

2. video_device：

struct video_device
{
    const struct v4l2_file_operations *fops;    /* 文件操作函数 */

    struct device dev;        /* v4l device */
    struct cdev *cdev;        /* character device */

    struct device *parent;        /* device parent */
    struct v4l2_device *v4l2_dev;    /* v4l2_device parent */

    /* Control handler associated with this device node. May be NULL. */
    struct v4l2_ctrl_handler *ctrl_handler;
    /* Priority state. If NULL, then v4l2_dev->prio will be used. */
    struct v4l2_prio_state *prio;

    /* device info */
    char name[];
    int vfl_type;
    /* 'minor' is set to -1 if the registration failed */
    int minor;
    u16 num;
...
    /* ioctl callbacks */
    const struct v4l2_ioctl_ops *ioctl_ops;        /* 控制函数 */

    /* serialization lock */
    struct mutex *lock;
};

3. v4l2-subdev：

struct v4l2_subdev {
#if defined(CONFIG_MEDIA_CONTROLLER)
    struct media_entity entity;
#endif
    struct list_head list;
    struct module *owner;
    u32 flags;
    struct v4l2_device *v4l2_dev;
    const struct v4l2_subdev_ops *ops;
    /* Never call these internal ops from within a driver! */
    const struct v4l2_subdev_internal_ops *internal_ops;
    /* The control handler of this subdev. May be NULL. */
    struct v4l2_ctrl_handler *ctrl_handler;
    /* name must be unique */
    char name[V4L2_SUBDEV_NAME_SIZE];
    /* can be used to group similar subdevs, value is driver-specific */
    u32 grp_id;
    /* pointer to private data */
    void *dev_priv;
    void *host_priv;
    /* subdev device node */
    struct video_device *devnode;
};

v4l2_device在v4l2框架中是v4l2_subdev的父设备

video_device是v4l2_device的上层结构体，存储v4l2_device数据和cdev，它会在/dev目录下生成设备节点文件

video_device的struct v4l2_ioctl_ops会在后面分析

在此我给出它的作用方便读者理解函数分析过程：

struct v4l2_ioctl_ops：它会在应用层使用ioctl()时根据传入的宏调用对应操作函数

二、核心层提供的注册函数

1. 注册和注销v4l2_device：

/* 注册 */
int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)

/* 注销 */
void v4l2_device_unregister(struct v4l2_device *v4l2_dev)

注册函数调用关系如下：

/* 将设备与v4l2_device捆绑，并把v4l2设备放到driver data中
 * 我们可以使用dev_get_drvdata(dev)获取到v4l2设备
 */
v4l2_device_register(&intf->dev, &dev->vdev)
  -> dev_set_drvdata(dev, v4l2_dev);
    -> dev->p->driver_data = data;    /* device->device_private为v4l2_device */

2. 注册和注销v4l2_subdev：

/* 注册 */
int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev, struct v4l2_subdev *sd)

/* 注销 */
void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)

注册函数调用关系如下：

v4l2_device_register_subdev()
  /* struct v4l2_ctrl_handler用于控制设备的亮度、饱和度等 */
  -> v4l2_ctrl_add_handler(v4l2_dev->ctrl_handler, sd->ctrl_handler);
    -> handler_new_ref(hdl, ctrl);         /* 设置控制属性 */
      -> v4l2_ctrl_new_std(hdl, NULL, class_ctrl, , , , )
        -> v4l2_ctrl_fill(id, &name, &type, &min, &max, &step, &def, &flags);
        -> v4l2_ctrl_new(hdl, ops, ...); /* ops为v4l2_ctrl_ops，定义控制函数 */
          -> list_add_tail(&ctrl->node, &hdl->ctrls);
  -> list_add_tail(&sd->list, &v4l2_dev->subdevs);

v4l2_subdev注册函数主要设置了设备的控制属性和控制函数，并把设备放入列表中

控制函数结构体定义如下，读者有印象即可

struct v4l2_ctrl_ops {
    int (*g_volatile_ctrl)(struct v4l2_ctrl *ctrl); /* 获取控制器值 */
    int (*try_ctrl)(struct v4l2_ctrl *ctrl);        /* 测试控制器值是否有效 */
    int (*s_ctrl)(struct v4l2_ctrl *ctrl);          /* 设置控制器值 */
};

3. 注册和注销video_device：

/* 注册 */
static inline int __must_check video_register_device(struct video_device *vdev, int type, int nr)

/* 注销 */
void video_unregister_device(struct video_device *vdev)

注册函数调用关系如下：

video_register_device(vdev, VFL_TYPE_GRABBER, -);
  -> __video_register_device(vdev, type, nr, , vdev->fops->owner);
    -> case VFL_TYPE_GRABBER:            /* 摄像头设备 */
      -> name_base = "video";
    -> case VFL_TYPE_GRABBER:
      -> minor_offset = ;
      -> minor_cnt = ;
    -> vdev->minor = i + minor_offset;
    -> vdev->cdev = cdev_alloc();
    -> vdev->cdev->ops = &v4l2_fops;
    -> cdev_add(vdev->cdev, MKDEV(VIDEO_MAJOR, vdev->minor), );  /* 依据次设备号分配cdev */
    -> dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num);    /* 设备名为video%d */
    -> device_register(&vdev->dev);
      -> device_add(dev);

video_register_device()函数主要分配、设置并注册了cdev和device。

三、v4l2_device和video_device的file_operations分析

分析到这里，产生了两个问题：

1. register_chrdev_region()和创建class在哪里被调用的？

2. v4l2_fops函数都做了什么？

我们先来决解第一个问题，两函数应该在初始化框架时被调用，初始化函数定义在v4l2-dev.c文件中：

 static int __init videodev_init(void)
 {
     dev_t dev = MKDEV(VIDEO_MAJOR, );        /* VIDEO_MAJOR = 81 */
     int ret;

     ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
 ...
     ret = class_register(&video_class);
 ...
     return ;
 }

现在我们来看v4l2_fops的定义：

static const struct file_operations v4l2_fops = {
    .owner = THIS_MODULE,
    .read = v4l2_read,
    .write = v4l2_write,
    .open = v4l2_open,
    .get_unmapped_area = v4l2_get_unmapped_area,
    .mmap = v4l2_mmap,
    .unlocked_ioctl = v4l2_ioctl,
    .release = v4l2_release,
    .poll = v4l2_poll,
    .llseek = no_llseek,
};

首先从open()函数分析：

 static int v4l2_open(struct inode *inode, struct file *filp)
 {
     struct video_device *vdev;
     int ret = ;
 ...
     vdev = video_devdata(filp);
 ...
     if (vdev->fops->open) {
 ...
         if (video_is_registered(vdev))
             ret = vdev->fops->open(filp);    /* 最终会调用video_device->fops的open()函数 */
 ...
     }
 ...
 }

read()和其他函数亦是如此：

 static ssize_t v4l2_read(struct file *filp, char __user *buf, size_t sz, loff_t *off)
 {
     struct video_device *vdev = video_devdata(filp);
 ...
     if (video_is_registered(vdev))
         ret = vdev->fops->read(filp, buf, sz, off);
 ...
 }

 static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
     struct video_device *vdev = video_devdata(filp);
     int ret = -ENODEV;

     if (vdev->fops->unlocked_ioctl) {
 ...
         if (video_is_registered(vdev))
             ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);
 ...
     }
 ...
 }

可以看到v4l2_fops定义的函数在底层都会调用video_device的fops函数，因此我们可以在SI4内核项目中搜索“struct v4l2_file_operations ”：

在此我以drivers/staging/media/solo6x10/v4l2.c文件为例分析

若读者使用它其他文件分析，可能在后面会遇到struct vb2_buffer、struct vb2_queue、struct vb2_ops和struct vb2_mem_ops，其实vb2就是videobuf2，是videobuf的新版本，在此不做介绍

文件链接：

https://files.cnblogs.com/files/Lioker/24_v4l2_xawtv.zip

static const struct v4l2_file_operations solo_v4l2_fops = {
    .owner          = THIS_MODULE,
    .open           = solo_v4l2_open,
    .release        = solo_v4l2_release,
    .read           = solo_v4l2_read,
    .poll           = solo_v4l2_poll,
    .mmap           = solo_v4l2_mmap,
    .ioctl          = video_ioctl2,
};

首先从open()函数分析：

solo_v4l2_open
  -> INIT_LIST_HEAD(&fh->vidq_active);    /* 初始化用于存放queue的list_head */
  -> solo_start_thread(fh);               /* 启动线程查询是否有数据 */
    -> solo_thread                        /* 等待数据 */
      -> DECLARE_WAITQUEUE(wait, current);
      -> add_wait_queue(&solo_dev->disp_thread_wait, &wait);
      -> schedule_timeout_interruptible(HZ);
      -> solo_thread_try(fh);             /* 如果有数据 */
        /* 取出等待队列头的第一个队列 */
        -> struct videobuf_buffer * vb = list_first_entry(&fh->vidq_active, struct videobuf_buffer, queue);
        -> list_del(&vb->queue);
        -> solo_fillbuf(fh, vb);
          -> wake_up(&vb->done);          /* 唤醒上层读写操作 */
      -> remove_wait_queue(&solo_dev->disp_thread_wait, &wait);
  -> videobuf_queue_sg_init(&fh->vidq,
         &solo_video_qops,   /* solo_video_qops为struct videobuf_queue_ops */
         ..., &fh->slock,    /* fh->slock为spinlock_t用于保护队列 */
         V4L2_BUF_TYPE_VIDEO_CAPTURE,     /* 是摄像头 */
         SOLO_DISP_PIX_FIELD,
         sizeof(struct videobuf_buffer), fh,...);

函数所使用的struct videobuf_queue、struct videobuf_queue_ops和struct videobuf_buffer会在后面分析

在此我给出它们的作用方便读者理解函数分析过程：

struct videobuf_queue：在数据传输过程中，首先把buffer放入queue，然后把queue放入list_head中，读写函数会通过操作list_head来操作queue中的buffer

struct videobuf_queue_ops：提供设置videobuf_buffer函数，添加queue到list_head函数，释放内存函数等

struct videobuf_buffer：用于数据传输，是数据传输的基本单位

函数所使用的videobuf_queue_sg_init()函数用于初始化queue，除此函数外，还有两函数可以用来初始化queue：

void videobuf_queue_vmalloc_init(struct videobuf_queue *q,
    struct videobuf_queue_ops *ops,
    struct device *dev,
    spinlock_t *irqlock,
    enum v4l2_buf_type type,
    enum v4l2_field field,
    unsigned int msize,
    void *priv);

void videobuf_queue_dma_contig_init(struct videobuf_queue *q,
    struct videobuf_queue_ops *ops,
    struct device *dev,
    spinlock_t *irqlock,
    enum v4l2_buf_type type,
    enum v4l2_field field,
    unsigned int msize,
    void *priv);

videobuf_queue_sg_init()：物理上和虚拟地址都是离散的buffer

videobuf_queue_vmalloc_init()：物理上离散的，但虚拟地址是连续的buffer

videobuf_queue_dma_contig_init()：物理上和虚拟地址都是连续的buffer

read()函数的调用关系如下：

solo_v4l2_read
  /* 从videobuf_queue fh->vidq取出数据 */
  -> videobuf_read_stream(&fh->vidq, data, count, ppos, , file->f_flags & O_NONBLOCK);
    -> q->read_buf = list_entry(q->stream.next, struct videobuf_buffer, stream);
    -> list_del(&q->read_buf->stream);

ioctl()函数的调用关系如下：

video_ioctl2
  /* 根据cmd，调用__video_do_ioctl()将数据拷贝到内核空间 */
  -> __video_do_ioctl
    -> struct v4l2_ioctl_ops *ops = vfd->ioctl_ops;
    -> case VIDIOC_QUERYCAP:    /* 设备支持的能力 */
      -> ops->vidioc_querycap(file, fh, cap);
    -> case VIDIOC_G_FMT:        /* 获取格式、分辨率等 */
      -> ps->vidioc_g_fmt_vid_cap(file, fh, f);
    -> case VIDIOC_QBUF:        /* 把缓存区放入传输队列 */
      -> ops->vidioc_qbuf(file, fh, p);
    -> case VIDIOC_DQBUF:        /* 把缓存从队列中取出 */
      -> ops->vidioc_dqbuf(file, fh, p);
    -> case VIDIOC_STREAMON:    /* 启动视频传输 */
      -> ops->vidioc_streamon(file, fh, i);
    -> case VIDIOC_STREAMOFF:    /* 关闭视频传输 */
      -> ops->vidioc_streamoff(file, fh, i);

分析完了这两个问题，下面我们来分析v4l2.c的init()函数

四、v4l2.c的init()函数分析

init()函数的调用关系：

solo_v4l2_init
  /* 初始化open()等函数使用的wait_queue_head_t */
  -> init_waitqueue_head(&solo_dev->disp_thread_wait);
  /* 分配、设置和注册video_device */
  -> solo_dev->vfd = video_device_alloc();
  -> *solo_dev->vfd = solo_v4l2_template;    /* struct video_device */
  -> video_register_device(solo_dev->vfd, VFL_TYPE_GRABBER, video_nr);

根据上述过程，我们可以得到下图：

五、数据传输和控制结构体分析

我在前几节有几个结构体没有介绍，在此我还是以v4l2.c文件的实例进行介绍

数据控制相关：

1. struct v4l2_ioctl_ops

static const struct v4l2_ioctl_ops solo_v4l2_ioctl_ops = {
    /* 表示它是一个摄像头设备 */
    .vidioc_querycap        = solo_querycap,
    /* 列举、获取、设置标准
     * 列举、获取标准使用的是
     * video_device的tvnorms和current_norm
     */
    .vidioc_s_std           = solo_s_std,
    /* 列举、获取、设置输入源 */
    .vidioc_enum_input      = solo_enum_input,
    .vidioc_s_input         = solo_set_input,
    .vidioc_g_input         = solo_get_input,
    /* 列举、获得、测试、设置摄像头的数据格式 */
    .vidioc_enum_fmt_vid_cap    = solo_enum_fmt_cap,
    .vidioc_try_fmt_vid_cap     = solo_try_fmt_cap,
    .vidioc_s_fmt_vid_cap       = solo_set_fmt_cap,
    .vidioc_g_fmt_vid_cap       = solo_get_fmt_cap,
     /* 缓冲区操作：申请、查询、放入队列、取出队列 */
    .vidioc_reqbufs         = solo_reqbufs,
    .vidioc_querybuf        = solo_querybuf,
    .vidioc_qbuf            = solo_qbuf,
    .vidioc_dqbuf           = solo_dqbuf,
    /* 启动、停止视频流 */
    .vidioc_streamon        = solo_streamon,
    .vidioc_streamoff       = solo_streamoff,
    /* Controls */
    .vidioc_queryctrl       = solo_disp_queryctrl,
    .vidioc_g_ctrl          = solo_disp_g_ctrl,
    .vidioc_s_ctrl          = solo_disp_s_ctrl,
};

数据传输相关：

1. struct videobuf_buffer

struct videobuf_buffer {
    unsigned int            i;
    u32                     magic;

    /* info about the buffer */
    unsigned int            width;          /* 摄像头图像像素长度 */
    unsigned int            height;          /* 宽度 */
    unsigned int            bytesperline; /* 一行的字节数 */
    unsigned long           size;          /* size = height * bytesperline */
    unsigned int            input;
    enum v4l2_field         field;
    enum videobuf_state     state;          /* 用于存储状态 */
    struct list_head        stream;        /* QBUF/DQBUF list */

    /* touched by irq handler */
    struct list_head        queue;
    wait_queue_head_t       done;
    unsigned int            field_count;
    struct timeval          ts;

    /* Memory type */
    enum v4l2_memory        memory;

    /* buffer size */
    size_t                  bsize;

    /* buffer offset (mmap + overlay) */
    size_t                  boff;

    /* buffer addr (userland ptr!) */
    unsigned long           baddr;

    /* for mmap'ed buffers */
    struct videobuf_mapping *map;

    /* Private pointer to allow specific methods to store their data */
    int            privsize;
    void                    *priv;
};

2. struct videobuf_queue

struct videobuf_queue {
    struct mutex           vb_lock;
    struct mutex           *ext_lock;
    spinlock_t             *irqlock;
    struct device           *dev;

    wait_queue_head_t       wait; /* wait if queue is empty */

    enum v4l2_buf_type         type;
    unsigned int               inputs; /* for V4L2_BUF_FLAG_INPUT */
    unsigned int               msize;
    enum v4l2_field            field;
    enum v4l2_field            last;   /* for field=V4L2_FIELD_ALTERNATE */
    struct videobuf_buffer     *bufs[VIDEO_MAX_FRAME];
    const struct videobuf_queue_ops  *ops;
    struct videobuf_qtype_ops  *int_ops;

    unsigned int               streaming:;
    unsigned int               reading:;

    /* capture via mmap() + ioctl(QBUF/DQBUF) */
    struct list_head           stream;

    /* capture via read() */
    unsigned int               read_off;
    struct videobuf_buffer     *read_buf;

    /* driver private data */
    void                       *priv_data;
};

3. struct videobuf_queue_ops

static struct videobuf_queue_ops solo_video_qops = {
    /* 被v4l2_ioctl_ops->vidioc_reqbufs调用，用于重新调整count和size */
    .buf_setup    = solo_buf_setup,
    /* 被v4l2_ioctl_ops->vidioc_qbuf调用，用于设置videobuf_buffer成员 */
    .buf_prepare    = solo_buf_prepare,
    /* 被v4l2_ioctl_ops->vidioc_qbuf调用，用于把queue放到list_head */
    .buf_queue    = solo_buf_queue,
    /* 被v4l2_ioctl_ops->vidioc_streamoff调用，用于释放内存 */
    .buf_release    = solo_buf_release,
};

当开始流I/O时，摄像头的图像会在应用和驱动间传输，它可能会有三个状态：

1. 在驱动的传入队列中，用户空间通过ioctl(..., VIDIOC_QBUF, ...)填充缓冲区，把缓冲区放入队列。

2. 在驱动的传出队列中，缓冲区已经填充了视频数据，等待用户空间读取

3. 在用户空间的队列中，用户空间已经通过ioctl(..., VIDIOC_DQBUF, ...)读取缓冲区了，此时驱动无法访问缓冲区

这三种状态的切换如下图：

六、虚拟摄像头驱动vivi.c虚拟机测试

本节我通过应用程序xawtv对vivi.c的系统调用的关系进行分析，我们需要做的有以下几步：

1. 执行$ sudo apt-get install xawtv在虚拟机中安装xawtv

2. 在网站https://www.kraxel.org/releases/xawtv/下载源码xawtv-3.95.tar.gz，并创建SI4工程

3. 虚拟机连接摄像头，执行$ ls /dev/video*可以看到生成了/dev/video0，执行xawtv即可看到图像

4. 执行$ uname -a，根据虚拟机内核版本去http://ftp.sjtu.edu.cn/sites/ftp.kernel.org/pub/linux/kernel/下载同版本的内核

5. 解压后把drivers/media/video目录单独取出，修改它的Makefile为：

KERN_DIR = /work/vmware/tools/linux-4.8

all:
    make -C $(KERN_DIR) M=`pwd` modules

clean:
    make -C $(KERN_DIR) M=`pwd` modules clean
    rm -rf modules.order

obj-m += vivi.o
obj-m += videobuf-core.o
obj-m += videobuf-vmalloc.o
obj-m += v4l2-common.o

6. 编译后，由于vivi.ko模块涉及较多文件，为防止有模块未被载入，我们可以使用$ sudo modprobe vivi加载内核自带vivi驱动及其所需框架和文件，然后依次执行$ sudo rmmod vivi和$ sudo insmod ./vivi.ko安装我们编译的vivi模块

7. 执行$ ls /dev/video*查看虚拟摄像头，然后执行$ xawtv -c /dev/videox打开虚拟摄像头

七、ioctl()执行过程和v4l2_ioctl_ops必需函数指针的确定

在可以看到图像后，我们就可以通过应用程序xawtv对应用程序ioctl()执行过程进行分析。

查看程序系统调用过程可以使用strace命令实现：

$ strace -o xawtv.log xawtv　　　　/* 执行xawtv命令，调用过程会存储在xawtv.log文件中 */

xawtv.log文件会放在上面的百度网盘分享链接中

首先，我们搜索“open("/dev/video”，我们只需要关注第二次open()，因为第一次open()后面有close()，可以看到文件描述符为4

接下来，我们搜索“(4, ”，查看有哪些对应文件描述符的操作：

 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\1\0\0\fbook-desktop\0\0010\0\22MIT-MAGIC-C"..., ) =
 read(, "", )                       =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "#\t$XdotOrg: lib/X11/nls/locale.a"..., ) =
 read(, "\t\t\t\t\tbg_BG.UTF-8\nbn_IN.utf8\t\t\t\t\t"..., ) =
 read(, "8859-15\t\t\t\tde_CH.ISO8859-15\nde_C"..., ) =
 read(, "_ZA.ISO8859-1\nen_ZA.ISO-8859-1\t\t"..., ) =
 read(, "85915\t\t\t\teu_ES.ISO8859-15\neu_ES."..., ) =
 read(, "14\ngv_GB.ISO-8859-14\t\t\t\tgv_GB.IS"..., ) =
 read(, "w_GB.ISO8859-1\nkw_GB.ISO-8859-1\t"..., ) =
 read(, ".ISO8859-1\noc\t\t\t\t\t\toc_FR.ISO8859"..., ) =
 read(, "r_RS.UTF-8\nsr_YU.UTF-8@cyrillic\t"..., ) =
 read(, "yi_US.CP1255\nzh_CN\t\t\t\t\t\tzh_CN.gb"..., ) =
 read(, ":00 dawes Exp $\n#\n\nPOSIX:\t\t\t\t\t\tC"..., ) =
 read(, "4:\t\t\t\tbr_FR.ISO8859-14\nbr_FR.ISO"..., ) =
 read(, "de_DE.88591.en:\t\t\t\t\tde_DE.ISO885"..., ) =
 read(, "59-1:\t\t\t\ten_ZA.ISO8859-1\nen_ZA.I"..., ) =
 read(, "_ES.ISO8859-1\neu_ES.iso88591:\t\t\t"..., ) =
 read(, "F-8\ngu_IN.utf8:\t\t\t\t\tgu_IN.UTF-8\n"..., ) =
 read(, "o_KR.utf8:\t\t\t\t\tko_KR.UTF-8\nKO_KR"..., ) =
 read(, "o_NO.utf8:\t\t\t\t\tno_NO.UTF-8\nnr:\t\t"..., ) =
 read(, "O8859-2\nsl_SI.iso88592:\t\t\t\t\tsl_S"..., ) =
 read(, "N\nvi_VN.tcvn5712:\t\t\t\t\tvi_VN.TCVN"..., ) =
 read(, "9-9\nturkish.iso88599:\t\t\t\ttr_TR.I"..., ) =
 read(, "", )                       =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "#\t$XdotOrg: lib/X11/nls/locale.d"..., ) =
 read(, "59-1/XLC_LOCALE\t\t\tes_AR.ISO8859-"..., ) =
 read(, "_FR.ISO8859-1\niso8859-15/XLC_LOC"..., ) =
 read(, "8/XLC_LOCALE\t\t\tbe_BY.UTF-8\nen_US"..., ) =
 read(, "en_US.UTF-8/XLC_LOCALE\t\t\tlo_LA.U"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "#  $Xorg: C,v 1.3 2000/08/17 19:"..., ) =
 read(, "", )                       =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "#\t$XdotOrg: lib/X11/nls/locale.a"..., ) =
 read(, "\t\t\t\t\tbg_BG.UTF-8\nbn_IN.utf8\t\t\t\t\t"..., ) =
 read(, "8859-15\t\t\t\tde_CH.ISO8859-15\nde_C"..., ) =
 read(, "_ZA.ISO8859-1\nen_ZA.ISO-8859-1\t\t"..., ) =
 read(, "85915\t\t\t\teu_ES.ISO8859-15\neu_ES."..., ) =
 read(, "14\ngv_GB.ISO-8859-14\t\t\t\tgv_GB.IS"..., ) =
 read(, "w_GB.ISO8859-1\nkw_GB.ISO-8859-1\t"..., ) =
 read(, ".ISO8859-1\noc\t\t\t\t\t\toc_FR.ISO8859"..., ) =
 read(, "r_RS.UTF-8\nsr_YU.UTF-8@cyrillic\t"..., ) =
 read(, "yi_US.CP1255\nzh_CN\t\t\t\t\t\tzh_CN.gb"..., ) =
 read(, ":00 dawes Exp $\n#\n\nPOSIX:\t\t\t\t\t\tC"..., ) =
 read(, "4:\t\t\t\tbr_FR.ISO8859-14\nbr_FR.ISO"..., ) =
 read(, "de_DE.88591.en:\t\t\t\t\tde_DE.ISO885"..., ) =
 read(, "59-1:\t\t\t\ten_ZA.ISO8859-1\nen_ZA.I"..., ) =
 read(, "_ES.ISO8859-1\neu_ES.iso88591:\t\t\t"..., ) =
 read(, "F-8\ngu_IN.utf8:\t\t\t\t\tgu_IN.UTF-8\n"..., ) =
 read(, "o_KR.utf8:\t\t\t\t\tko_KR.UTF-8\nKO_KR"..., ) =
 read(, "o_NO.utf8:\t\t\t\t\tno_NO.UTF-8\nnr:\t\t"..., ) =
 read(, "O8859-2\nsl_SI.iso88592:\t\t\t\t\tsl_S"..., ) =
 read(, "N\nvi_VN.tcvn5712:\t\t\t\t\tvi_VN.TCVN"..., ) =
 read(, "9-9\nturkish.iso88599:\t\t\t\ttr_TR.I"..., ) =
 read(, "", )                       =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "#\t$XdotOrg: lib/X11/nls/locale.d"..., ) =
 read(, "59-1/XLC_LOCALE\t\t\tes_AR.ISO8859-"..., ) =
 read(, "_FR.ISO8859-1\niso8859-15/XLC_LOC"..., ) =
 read(, "8/XLC_LOCALE\t\t\tbe_BY.UTF-8\nen_US"..., ) =
 read(, "en_US.UTF-8/XLC_LOCALE\t\t\tlo_LA.U"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "#  $Xorg: C,v 1.3 2000/08/17 19:"..., ) =
 read(, "", )                       =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "# Locale name alias data base.\n#"..., ) =
 read(, "", )                       =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFDIR|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "#\t$XdotOrg: lib/X11/nls/locale.a"..., ) =
 read(, "\t\t\t\t\tbg_BG.UTF-8\nbn_IN.utf8\t\t\t\t\t"..., ) =
 read(, "8859-15\t\t\t\tde_CH.ISO8859-15\nde_C"..., ) =
 read(, "_ZA.ISO8859-1\nen_ZA.ISO-8859-1\t\t"..., ) =
 read(, "85915\t\t\t\teu_ES.ISO8859-15\neu_ES."..., ) =
 read(, "14\ngv_GB.ISO-8859-14\t\t\t\tgv_GB.IS"..., ) =
 read(, "w_GB.ISO8859-1\nkw_GB.ISO-8859-1\t"..., ) =
 read(, ".ISO8859-1\noc\t\t\t\t\t\toc_FR.ISO8859"..., ) =
 read(, "r_RS.UTF-8\nsr_YU.UTF-8@cyrillic\t"..., ) =
 read(, "yi_US.CP1255\nzh_CN\t\t\t\t\t\tzh_CN.gb"..., ) =
 read(, ":00 dawes Exp $\n#\n\nPOSIX:\t\t\t\t\t\tC"..., ) =
 read(, "4:\t\t\t\tbr_FR.ISO8859-14\nbr_FR.ISO"..., ) =
 read(, "de_DE.88591.en:\t\t\t\t\tde_DE.ISO885"..., ) =
 read(, "59-1:\t\t\t\ten_ZA.ISO8859-1\nen_ZA.I"..., ) =
 read(, "_ES.ISO8859-1\neu_ES.iso88591:\t\t\t"..., ) =
 read(, "F-8\ngu_IN.utf8:\t\t\t\t\tgu_IN.UTF-8\n"..., ) =
 read(, "o_KR.utf8:\t\t\t\t\tko_KR.UTF-8\nKO_KR"..., ) =
 read(, "o_NO.utf8:\t\t\t\t\tno_NO.UTF-8\nnr:\t\t"..., ) =
 read(, "O8859-2\nsl_SI.iso88592:\t\t\t\t\tsl_S"..., ) =
 read(, "N\nvi_VN.tcvn5712:\t\t\t\t\tvi_VN.TCVN"..., ) =
 read(, "9-9\nturkish.iso88599:\t\t\t\ttr_TR.I"..., ) =
 read(, "", )                       =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "#\t$XdotOrg: lib/X11/nls/locale.a"..., ) =
 read(, "\t\t\t\t\tbg_BG.UTF-8\nbn_IN.utf8\t\t\t\t\t"..., ) =
 read(, "8859-15\t\t\t\tde_CH.ISO8859-15\nde_C"..., ) =
 read(, "_ZA.ISO8859-1\nen_ZA.ISO-8859-1\t\t"..., ) =
 read(, "85915\t\t\t\teu_ES.ISO8859-15\neu_ES."..., ) =
 read(, "14\ngv_GB.ISO-8859-14\t\t\t\tgv_GB.IS"..., ) =
 read(, "w_GB.ISO8859-1\nkw_GB.ISO-8859-1\t"..., ) =
 read(, ".ISO8859-1\noc\t\t\t\t\t\toc_FR.ISO8859"..., ) =
 read(, "r_RS.UTF-8\nsr_YU.UTF-8@cyrillic\t"..., ) =
 read(, "yi_US.CP1255\nzh_CN\t\t\t\t\t\tzh_CN.gb"..., ) =
 read(, ":00 dawes Exp $\n#\n\nPOSIX:\t\t\t\t\t\tC"..., ) =
 read(, "4:\t\t\t\tbr_FR.ISO8859-14\nbr_FR.ISO"..., ) =
 read(, "de_DE.88591.en:\t\t\t\t\tde_DE.ISO885"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "#\t$XdotOrg: lib/X11/nls/locale.d"..., ) =
 read(, "59-1/XLC_LOCALE\t\t\tes_AR.ISO8859-"..., ) =
 read(, "_FR.ISO8859-1\niso8859-15/XLC_LOC"..., ) =
 read(, "8/XLC_LOCALE\t\t\tbe_BY.UTF-8\nen_US"..., ) =
 read(, "en_US.UTF-8/XLC_LOCALE\t\t\tlo_LA.U"..., ) =
 read(, "LE:\t\t\taf_ZA.ISO8859-1\niso8859-15"..., ) =
 read(, "LE:\t\t\tes_MX.ISO8859-1\niso8859-1/"..., ) =
 read(, "9-2/XLC_LOCALE:\t\t\tpl_PL.ISO8859-"..., ) =
 read(, "           byn_ER.UTF-8\nen_US.UT"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "#  $XFree86: xc/nls/XLC_LOCALE/e"..., ) =
 read(, "GB2312.1980-0:GL; GB2312.1980-0:"..., ) =
 read(, "", )                       =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\n! -----------------------------"..., ) =
 fcntl64(, F_GETFD)                     = 0x1 (flags FD_CLOEXEC)
 getdents64(, /* 19 entries */, )  =
 getdents64(, /* 0 entries */, )   =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\240\3\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\320\v\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\220\3\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\240\17\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0000'\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\0\17\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0@\22\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\360\30\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\0\6\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\240\4\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0P\4\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0`\4\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\240\3\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\240\3\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\200\10\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\260\n\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\3405\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\220\r\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\220\10\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\240\7\0\0004\0\0\0"..., ) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 fstat64(, {st_mode=S_IFREG|, st_size=, ...}) =
 read(, "! $Xorg: XKeysymDB,v 1.3 2000/08"..., ) =
 ioctl(, VIDIOC_QUERYCAP or VT_OPENQRY, 0x9b40998) = - EINVAL (Invalid argument)
 ioctl(, VIDIOC_QUERYCAP or VT_OPENQRY, 0xbfaccd44) =
 ioctl(, VIDIOC_G_FMT or VT_SENDSIG, 0xbfaccc78) =
 ioctl(, VIDIOC_ENUM_FMT or VT_SETMODE, 0xbfaccbec) =
 ioctl(, 0xc02c564a, 0xbfaccb58)        = - EINVAL (Invalid argument)
 ioctl(, VIDIOC_ENUM_FMT or VT_SETMODE, 0xbfaccbec) =
 ioctl(, 0xc02c564a, 0xbfaccb58)        = - EINVAL (Invalid argument)
 ioctl(, VIDIOC_ENUM_FMT or VT_SETMODE, 0xbfaccbec) =
 ioctl(, 0xc02c564a, 0xbfaccb58)        = - EINVAL (Invalid argument)
 ioctl(, VIDIOC_ENUM_FMT or VT_SETMODE, 0xbfaccbec) =
 ioctl(, VIDIOC_ENUM_FMT or VT_SETMODE, 0xbfaccbec) =
 ioctl(, VIDIOC_ENUM_FMT or VT_SETMODE, 0xbfaccbec) =
 ioctl(, VIDIOC_ENUM_FMT or VT_SETMODE, 0xbfaccbec) = - EINVAL (Invalid argument)
 ioctl(, VIDIOC_QUERYCAP or VT_OPENQRY, 0xbfaccb84) =
 ioctl(, VIDIOC_G_INPUT, 0xbfacca2c)    =
 ioctl(, VIDIOC_ENUMINPUT, 0xbfacca2c)  =
 fstat64(, {st_mode=S_IFCHR|, st_rdev=makedev(, ), ...}) =
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0xbfacca78) = - EINVAL (Invalid argument)
 ioctl(, VIDIOC_QUERYCAP or VT_OPENQRY, 0x9b40998) =
 fcntl64(, F_SETFD, FD_CLOEXEC)         =
 ioctl(, VIDIOC_ENUMINPUT, 0x9b40acc)   =
 ioctl(, VIDIOC_ENUMINPUT, 0x9b40b18)   =
 ioctl(, VIDIOC_ENUMINPUT, 0x9b40b64)   =
 ioctl(, VIDIOC_ENUMINPUT, 0x9b40bb0)   =
 ioctl(, VIDIOC_ENUMINPUT, 0x9b40bfc)   = - EINVAL (Invalid argument)
 ioctl(, VIDIOC_ENUMSTD, 0x9b40f8c)     =
 ioctl(, VIDIOC_ENUMSTD, 0x9b40fcc)     =
 ioctl(, VIDIOC_ENUMSTD, 0x9b4100c)     =
 ioctl(, VIDIOC_ENUMSTD, 0x9b4104c)     =
 ioctl(, VIDIOC_ENUMSTD, 0x9b4108c)     =
 ioctl(, VIDIOC_ENUMSTD, 0x9b410cc)     =
 ioctl(, VIDIOC_ENUMSTD, 0x9b4110c)     =
 ioctl(, VIDIOC_ENUMSTD, 0x9b4114c)     = - EINVAL (Invalid argument)
 ioctl(, VIDIOC_ENUM_FMT or VT_SETMODE, 0x9b4138c) =
 ioctl(, VIDIOC_ENUM_FMT or VT_SETMODE, 0x9b413cc) =
 ioctl(, VIDIOC_ENUM_FMT or VT_SETMODE, 0x9b4140c) =
 ioctl(, VIDIOC_ENUM_FMT or VT_SETMODE, 0x9b4144c) =
 ioctl(, VIDIOC_ENUM_FMT or VT_SETMODE, 0x9b4148c) =
 ioctl(, VIDIOC_ENUM_FMT or VT_SETMODE, 0x9b414cc) =
 ioctl(, VIDIOC_G_PARM, 0x9b40a00)      =
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41b8c) =
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41bd0) =
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41c14) =
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41c58) =
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41c9c) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41ce0) =
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41d24) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41d68) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41dac) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41df0) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41e34) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41e78) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41ebc) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41f00) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41f44) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41f88) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b41fcc) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42010) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42054) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42098) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b420dc) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42120) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42164) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b421a8) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b421ec) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42230) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42274) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b422b8) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b422fc) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42340) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42384) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b423c8) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b4240c) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42450) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42494) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b424d8) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b4251c) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42560) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b425a4) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b425e8) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b4262c) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42670) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b426b4) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b426f8) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b4273c) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42780) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b427c4) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42808) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b4284c) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42890) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b428d4) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42918) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b4295c) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b429a0) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b429e4) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42a28) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42a6c) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42ab0) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42af4) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42b38) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42b7c) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42bc0) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42c04) = - EINVAL (Invalid argument)
 ioctl(, MATROXFB_TVOQUERYCTRL or VIDIOC_QUERYCTRL, 0x9b42c48) = - EINVAL (Invalid argument)
 ioctl(, VIDIOC_G_STD, 0xbfacce08)      =
 ioctl(, VIDIOC_G_INPUT, 0xbfacce1c)    =
 ioctl(, MATROXFB_G_TVOCTRL or VIDIOC_G_CTRL, 0xbfacce14) =
 ioctl(, MATROXFB_G_TVOCTRL or VIDIOC_G_CTRL, 0xbfacce14) =
 ioctl(, MATROXFB_G_TVOCTRL or VIDIOC_G_CTRL, 0xbfacce14) =
 ioctl(, MATROXFB_G_TVOCTRL or VIDIOC_G_CTRL, 0xbfacce14) =
 ioctl(, MATROXFB_G_TVOCTRL or VIDIOC_G_CTRL, 0xbfacce24) =
 ioctl(, VIDIOC_TRY_FMT, 0x9b42ca4)     =
 ioctl(, VIDIOC_S_FMT or VT_RELDISP, 0xbfacc754) =
 ioctl(, VIDIOC_TRY_FMT, 0x9b42ca4)     =
 ioctl(, VIDIOC_REQBUFS or VT_DISALLOCATE, 0x9b42d80) =
 ioctl(, VIDIOC_QUERYBUF or VT_RESIZE, 0x9b42d94) =
 ioctl(, VIDIOC_QUERYBUF or VT_RESIZE, 0x9b42dd8) =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_STREAMON, 0xbfacca2c)   =
 ioctl(, MATROXFB_S_TVOCTRL or VIDIOC_S_CTRL, 0xbfacce10) =
 ioctl(, MATROXFB_S_TVOCTRL or VIDIOC_S_CTRL, 0xbfacce10) =
 ioctl(, MATROXFB_S_TVOCTRL or VIDIOC_S_CTRL, 0xbfacce10) =
 ioctl(, MATROXFB_S_TVOCTRL or VIDIOC_S_CTRL, 0xbfacce10) =
 ioctl(, VIDIOC_S_INPUT, 0xbfacce84)    =
 ioctl(, VIDIOC_S_STD, 0x9b40f90)       =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42dd8)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_QBUF, 0x9b42d94)        =
 ioctl(, VIDIOC_DQBUF, 0xbfaccd00)      =
 ioctl(, VIDIOC_STREAMOFF, 0xbfacc53c)  =
 ioctl(, VIDIOC_QUERYBUF or VT_RESIZE, 0xbfacc48c) =
 ioctl(, VIDIOC_QUERYBUF or VT_RESIZE, 0xbfacc48c) =
 ioctl(, VIDIOC_REQBUFS or VT_DISALLOCATE, 0x9b42d80) = - EINVAL (Invalid argument)
 ioctl(, VIDIOC_TRY_FMT, 0x9b42ca4)     = - EINVAL (Invalid argument)
 ioctl(, VIDIOC_TRY_FMT, 0xbfacc000)    =
 ioctl(, VIDIOC_TRY_FMT, 0xbfacc000)    =
 ioctl(, VIDIOC_TRY_FMT, 0xbfacc000)    =
 ioctl(, VIDIOC_TRY_FMT, 0xbfacc000)    =
 ioctl(, VIDIOC_TRY_FMT, 0xbfacc000)    =
 ioctl(, VIDIOC_TRY_FMT, 0xbfacc000)    =
 ioctl(, VIDIOC_REQBUFS or VT_DISALLOCATE, 0xbfacc70c) =
 ioctl(, VIDIOC_QUERYBUF or VT_RESIZE, 0xbfacc61c) =
 ioctl(, VIDIOC_QUERYBUF or VT_RESIZE, 0xbfacc61c) =
 ioctl(, VIDIOC_QBUF, 0xbfacc61c)       =
 ioctl(, VIDIOC_QBUF, 0xbfacc61c)       =
 ioctl(, VIDIOC_STREAMON, 0xbfacc65c)   =
 ioctl(, VIDIOC_DQBUF, 0xbfacc6c8)      =
 ioctl(, VIDIOC_QBUF, 0xbfacc61c)       = 

xawtv.log文件中open()函数之后调用了ioctl(4, VIDIOC_QUERYCAP, ...)，因此文件描述符操作ioctl(4, VIDIOC_QUERYCAP, ...)上面的所有行不会涉及驱动底层

最后，我们可以根据文件描述符操作文件、xawtv.log和SI4工程确定ioctl()执行过程：

open("/dev/video0", O_RDWR|O_LARGEFILE)    /* 1. 打开video0 */
ioctl(, VIDIOC_QUERYCAP         /* 2. 列举性能 */
ioctl(, VIDIOC_G_FMT            /* 3. 获得格式 */
for ()
  -> ioctl(, VIDIOC_ENUM_FMT    /* 4. 列举格式 */
ioctl(, VIDIOC_QUERYCAP         /* 5.  */
ioctl(, VIDIOC_G_INPUT          /* 6. 获取当前输入源 */
ioctl(, VIDIOC_ENUMINPUT        /* 7. 列举输入源 */
ioctl(, VIDIOC_QUERYCTRL        /* 8. 查询属性，如亮度范围、对比度范围 */
ioctl(, VIDIOC_QUERYCAP         /* 9.  */
ioctl(, VIDIOC_ENUMINPUT        /* 10. */
for ()
  -> ioctl(, VIDIOC_ENUMINPUT   /* 11. */
for ()
  -> ioctl(, VIDIOC_ENUMSTD     /* 12.列举标准 */
for ()
  -> ioctl(, VIDIOC_ENUM_FMT    /* 13. */
ioctl(, VIDIOC_G_PARM           /* 14. */
for ()
  -> ioctl(, VIDIOC_QUERYCTRL   /* 15. */
ioctl(, VIDIOC_G_STD            /* 16.获取当前使用的标准 */
ioctl(, VIDIOC_G_INPUT          /* 17. */
ioctl(, VIDIOC_G_CTRL           /* 18.获取当前所使用的属性 */
ioctl(, VIDIOC_TRY_FMT          /* 19.测试摄像头支持的格式 */
ioctl(, VIDIOC_S_FMT            /* 20.设置摄像头格式 */
ioctl(, VIDIOC_REQBUFS          /* 21.请求系统分配缓冲区 */
ioctl(, VIDIOC_QUERYBUF         /* 22.查询所分配的缓冲区 */
for ()
  -> ioctl(, VIDIOC_QBUF        /* 23.把缓冲区放入队列 */
ioctl(, VIDIOC_STREAMON         /* 24.启动摄像头 */
for ()
  -> ioctl(, VIDIOC_S_CTRL      /* 25.设置属性 */
ioctl(, VIDIOC_S_INPUT          /* 26.设置输入源 */
ioctl(, VIDIOC_S_STD            /* 27.设置标准 */
for ()
  -> select(, []               /* 28.查询文件描述符4是否有数据 */
  -> ioctl(, VIDIOC_DQBUF       /* 29.把缓冲区从队列中取出 */
  -> /* 处理数据 */
  -> ioctl(, VIDIOC_QBUF        /* 30.把缓冲区放入队列 */
ioctl(, VIDIOC_STREAMOFF        /* 31.关闭摄像头 */

在分析完ioctl()的执行过程后，我们需要在SI4工程文件drv0-v4l2.c文件中搜索ioctl()各个宏，确定v4l2_ioctl_ops必需的函数指针：

/** 1~2被v4l2_open(char *device)调用 */
open("/dev/video0", O_RDWR|O_LARGEFILE)    /* 1. 打开video0 */
ioctl(, VIDIOC_QUERYCAP         /* 2. 列举性能 */

/** 3~10没有看到调用过程，可能源码和应用程序不一致，略 */

/** 11~15被get_device_capabilities(h)调用 */
for ()
  -> ioctl(, VIDIOC_ENUMINPUT   /* 11. */
for ()
  -> ioctl(, VIDIOC_ENUMSTD     /* 12.列举标准 */
for ()
  -> ioctl(, VIDIOC_ENUM_FMT    /* 13. */
ioctl(, VIDIOC_G_PARM           /* 14. */
for ()
  -> ioctl(, VIDIOC_QUERYCTRL   /* 15. */

/** 16~18被v4l2_read_attr()调用 */
ioctl(, VIDIOC_G_STD            /* 16.获取当前使用的标准 */
ioctl(, VIDIOC_G_INPUT          /* 17. */
ioctl(, VIDIOC_G_CTRL           /* 18.获取当前所使用的属性 */

/** 19~20被v4l2_overlay()调用 */
ioctl(, VIDIOC_TRY_FMT          /* 19.测试摄像头支持的格式 */
ioctl(, VIDIOC_S_FMT            /* 20.设置摄像头格式 */

/** 21~24被v4l2_start_streaming()调用 */
ioctl(, VIDIOC_REQBUFS          /* 21.请求系统分配缓冲区 */
ioctl(, VIDIOC_QUERYBUF         /* 22.查询所分配的缓冲区 */
for ()
  -> ioctl(, VIDIOC_QBUF        /* 23.把缓冲区放入队列 */
  -> h->buf_me[i].data = mmap(...);
ioctl(, VIDIOC_STREAMON         /* 24.启动摄像头 */

/** 25~27被v4l2_write_attr()调用 */
ioctl(, VIDIOC_S_CTRL           /* 25.设置属性 */
ioctl(, VIDIOC_S_INPUT          /* 26.设置输入源 */
ioctl(, VIDIOC_S_STD            /* 27.设置标准 */

/** 28~29被v4l2_waiton()调用
 *  30被v4l2_queue_buffer()调用
 *  v4l2_waiton()和v4l2_queue_buffer()被v4l2_nextframe()调用
 */
for ()
  -> select(, []               /* 28.查询文件描述符4是否有数据 */
  -> ioctl(, VIDIOC_DQBUF       /* 29.把缓冲区从队列中取出 */
  -> /* 处理数据，之前使用mmap()获得了缓冲区的地址 */
  -> ioctl(, VIDIOC_QBUF        /* 30.把缓冲区放入队列 */
/** 31被v4l2_stop_streaming()调用  */
ioctl(, VIDIOC_STREAMOFF        /* 31.关闭摄像头 */

剩下这么多宏，有哪个是可以省略的呢？

我们现在要回到虚拟机内核的vivi.c中vivi_ioctl_ops逐个测试，测试方法为：注释某个函数指针，重新编译挂载，测试是否可以正常使用。

我在此不再一一测试，最终结果如下：

static const struct v4l2_ioctl_ops vivi_ioctl_ops = {
    /* 表示它是一个摄像头设备。不可省略 */
    .vidioc_querycap      = vidioc_querycap,
#if 0
    /* 列举、获取、设置输入源。可以省略，使用默认输入源 */
    .vidioc_enum_input    = vidioc_enum_input,
    .vidioc_g_input       = vidioc_g_input,
    .vidioc_s_input       = vidioc_s_input,
#endif
    /* 列举、获得、测试、设置摄像头的数据格式。不可省略 */
    .vidioc_enum_fmt_vid_cap  = vidioc_enum_fmt_vid_cap,
    .vidioc_g_fmt_vid_cap     = vidioc_g_fmt_vid_cap,
    .vidioc_try_fmt_vid_cap   = vidioc_try_fmt_vid_cap,
    .vidioc_s_fmt_vid_cap     = vidioc_s_fmt_vid_cap,

    /* 缓冲区操作：申请、查询、放入队列、取出队列。不可省略 */
    .vidioc_reqbufs       = vidioc_reqbufs,
    .vidioc_querybuf      = vidioc_querybuf,
    .vidioc_qbuf          = vidioc_qbuf,
    .vidioc_dqbuf         = vidioc_dqbuf,
#if 0
    /* 列举、获取、设置标准。可以省略
     * 列举、获取标准使用的是
     * video_device的tvnorms和current_norm
     */
    .vidioc_s_std         = vidioc_s_std,
#endif
    /* 启动、停止视频流。不可省略 */
    .vidioc_streamon      = vidioc_streamon,
    .vidioc_streamoff     = vidioc_streamoff,
#if 0
    /* 在内核日志中记录状态。可以省略 */
    .vidioc_log_status    = v4l2_ctrl_log_status,
    /* 子系统事件。可以省略 */
    .vidioc_subscribe_event = v4l2_ctrl_subscribe_event,
    .vidioc_unsubscribe_event = v4l2_event_unsubscribe,
#endif
};

八、数据的获取过程

本节使用v4l2.c进行分析，读者若对vb2感兴趣也可以分析vivi.c

1. 请求分配缓冲区，但此阶段其实只分配了videobuf_buffer

ioctl(, VIDIOC_REQBUFS
  -> solo_reqbufs
    -> videobuf_reqbufs(&fh->vidq, req);
      -> *size = solo_image_size(solo_dev);        /* 设置图片size */
      -> __videobuf_mmap_setup(q, count, size, req->memory);
        -> q->bufs[i] = videobuf_alloc_vb(q);    /* 分配设置videobuf_buffer */

2. 查询映射缓冲区，通过videobuf_buffer设置供上层使用的v4l2_buffer

ioctl(, VIDIOC_QUERYBUF
  -> videobuf_querybuf
    -> videobuf_status(q, b, q->bufs[b->index], q->type);
      -> b->flags |= V4L2_BUF_FLAG_MAPPED;
      -> b->field     = vb->field;
      -> b->timestamp = vb->ts;            /* v4l2_buffer */

3. 真正分配缓冲区

mmap(NULL, h->buf_v4l2[i].length, ...)
  -> solo_v4l2_mmap
    -> videobuf_mmap_mapper(&fh->vidq, vma);
      -> CALL(q, mmap_mapper, q, buf, vma)

4. 把缓冲区放入队列

ioctl(, VIDIOC_QBUF
  -> videobuf_qbuf(&fh->vidq, buf);
    -> buf = q->bufs[b->index];
    -> solo_buf_prepare            /* 设置video_device成员 */
      -> vb->width  = solo_dev->video_hsize;
      -> vb->height = solo_vlines(solo_dev);
    -> list_add_tail(&buf->stream, &q->stream)
    -> solo_buf_queue            /* 把queue放到list_head */
      -> list_add_tail(&vb->queue, &fh->vidq_active);

5. 启动摄像头

ioctl(, VIDIOC_STREAMON
  -> solo_streamon
    -> videobuf_streamon(&fh->vidq);
      -> solo_buf_queue            /* 把queue放到list_head */
        -> list_add_tail(&vb->queue, &fh->vidq_active);
      -> wake_up_interruptible_sync(&q->wait);

6. 查询是否有数据

select(h->fd + , &rdset, NULL, NULL, &tv)
  -> solo_v4l2_poll
    -> videobuf_poll_stream(file, &fh->vidq, wait);
      -> poll_wait(file, &buf->done, wait);

唤醒此进程的是open()函数注册的solo_thread()函数

7. 从缓冲区中取数据

ioctl(, VIDIOC_DQBUF
  -> solo_dqbuf
    -> videobuf_dqbuf(&fh->vidq, buf, file->f_flags & O_NONBLOCK);
      -> stream_next_buffer(q, &buf, nonblocking);    /* 在queue中获取有数据的缓冲区 */
      -> videobuf_status(q, b, buf, q->type);        /* 把缓冲区的状态返回给应用层 */
      -> list_del(&buf->stream);

九、虚拟摄像头驱动程序编写过程

1. 使用video_device_alloc()分配video_device

2. 设置结构体成员

.fops

.ioctl_ops（里面需要设置11项）

如果要用内核提供的缓冲区操作函数，还需要构造一个videobuf_queue_ops

3. 使用video_register_device()注册video_device

我们可以仿照v4l2.c写一个虚拟摄像头驱动程序

源代码：

 #include <linux/module.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/fs.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/mm.h>
 #include <linux/ioport.h>
 #include <linux/init.h>
 #include <linux/sched.h>
 #include <linux/pci.h>
 #include <linux/random.h>
 #include <linux/version.h>
 #include <linux/mutex.h>
 #include <linux/videodev2.h>
 #include <linux/dma-mapping.h>
 #include <linux/interrupt.h>
 #include <linux/kthread.h>
 #include <linux/highmem.h>
 #include <linux/freezer.h>
 #include <media/videobuf-vmalloc.h>
 #include <media/v4l2-device.h>
 #include <media/v4l2-ioctl.h>

 #define USE_DMA        0

 static struct video_device *myvivi;
 static struct v4l2_format myvivi_format;
 static struct videobuf_queue myvivi_vb_vidq;
 static spinlock_t myvivi_slock;
 static struct timer_list myvivi_timer;
 static struct list_head myvivi_list_head;

 /**
  *   videobuf_queue_ops
  **/
 /* ioctl VIDIOC_REQBUFS导致此函数被调用
  * 用于重新调整count和size
  */
 static int myvivi_buf_setup(struct videobuf_queue *vq, unsigned int *count, unsigned int *size)
 {
     *size = myvivi_format.fmt.pix.sizeimage;

     if (*count < )
         *count = ;

     return ;
 }

 /* ioctl VIDIOC_QBUF导致此函数被调用
  * 它会填充video_buffer结构体并调用videobuf_iolock来分配内存
  */
 static int myvivi_buf_prepare(struct videobuf_queue *vq, struct videobuf_buffer *vb, enum v4l2_field field)
 {
     vb->size    = myvivi_format.fmt.pix.sizeimage;

     /* XXX: These properties only change when queue is idle */
     vb->width    = myvivi_format.fmt.pix.width;
     vb->height    = myvivi_format.fmt.pix.height;
     vb->bytesperline = myvivi_format.fmt.pix.bytesperline;
     vb->field  = field;
 #if USE_DMA
     if (vb->state == VIDEOBUF_NEEDS_INIT) {
         int rc = videobuf_iolock(vq, vb, NULL);
         if (rc < ) {
             struct videobuf_dmabuf *dma = videobuf_to_dma(vb);
             videobuf_dma_unmap(vq->dev, dma);
             videobuf_dma_free(dma);
             vb->state = VIDEOBUF_NEEDS_INIT;
             return rc;
         }
     }
 #endif
     vb->state = VIDEOBUF_PREPARED;

     return ;
 }

 /* ioctl VIDIOC_QBUF时：
  * 1. 调用buf_prepare()做准备工作
  * 2. 把buf放入stream队列
  * 3. 调用buf_queue（起通知、记录作用）
  */
 static void myvivi_buf_queue(struct videobuf_queue *vq, struct videobuf_buffer *vb)
 {
     vb->state = VIDEOBUF_QUEUED;
     list_add_tail(&vb->queue, &myvivi_list_head);
     /* 使用的定时器，不需要唤醒 */
 //    wake_up_interruptible(&solo_dev->disp_thread_wait);
 }

 /* APP不再使用队列时，用它来释放内存 */
 static void myvivi_buf_release(struct videobuf_queue *vq, struct videobuf_buffer *vb)
 {
 #if USE_DMA
     struct videobuf_dmabuf *dma = videobuf_to_dma(vb);

     videobuf_dma_unmap(vq->dev, dma);
     videobuf_dma_free(dma);
 #endif
     vb->state = VIDEOBUF_NEEDS_INIT;
 }

 static struct videobuf_queue_ops solo_video_qops = {
     .buf_setup        = myvivi_buf_setup,
     .buf_prepare    = myvivi_buf_prepare,
     .buf_queue        = myvivi_buf_queue,
     .buf_release    = myvivi_buf_release,
 };

 /**
  *   v4l2_file_operations
  **/
 static int myvivi_open(struct file *file)
 {
     videobuf_queue_vmalloc_init(&myvivi_vb_vidq, &solo_video_qops,
                    NULL, &myvivi_slock,
                    V4L2_BUF_TYPE_VIDEO_CAPTURE,
                    V4L2_FIELD_INTERLACED,
                    sizeof(struct videobuf_buffer), NULL, NULL);
     /* 其他程序在此处执行thread，本程序在此处执行定时器 */
     myvivi_timer.expires = jiffies + ;
     add_timer(&myvivi_timer);

     return ;
 }

 static int myvivi_close(struct file *file)
 {
     del_timer(&myvivi_timer);
     videobuf_stop(&myvivi_vb_vidq);
     videobuf_mmap_free(&myvivi_vb_vidq);

     return ;
 }

 static ssize_t myvivi_read(struct file *file, char __user *data, size_t count, loff_t *ppos)
 {
     return videobuf_read_stream(&myvivi_vb_vidq, data, count, ppos, , file->f_flags & O_NONBLOCK);
 }

 static unsigned int myvivi_poll(struct file *file, struct poll_table_struct *wait)
 {
     return videobuf_poll_stream(file, &myvivi_vb_vidq, wait);
 }

 extern int videobuf_mmap_mapper(struct videobuf_queue *, struct vm_area_struct *);
 static int myvivi_mmap(struct file *file, struct vm_area_struct *vma)
 {
     return videobuf_mmap_mapper(&myvivi_vb_vidq, vma);
 }

 static const struct v4l2_file_operations myvivi_fops = {
     .owner            = THIS_MODULE,
     .open           = myvivi_open,
     .release        = myvivi_close,
     .read           = myvivi_read,
     .poll            = myvivi_poll,
     .unlocked_ioctl = video_ioctl2,
     .mmap           = myvivi_mmap,
 };

 /**
  *   v4l2_ioctl_ops
  **/
 static int myvivi_querycap(struct file *file, void  *priv, struct v4l2_capability *cap)
 {
     strcpy(cap->driver, "myvivi");
     strcpy(cap->card, "myvivi");
     cap->version = 0x01;
     cap->capabilities = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
     return ;
 }

 static int myvivi_enum_fmt_vid_cap(struct file *file, void  *priv, struct v4l2_fmtdesc *f)
 {
     if (f->index)
         return -EINVAL;

     f->pixelformat = V4L2_PIX_FMT_YUYV;
     strlcpy(f->description, "4:2:2, packed, YUYV", sizeof(f->description));

     return ;
 }

 static int myvivi_g_fmt_vid_cap(struct file *file, void *priv, struct v4l2_format *f)
 {
     memcpy(f, &myvivi_format, sizeof(myvivi_format));
     return ;
 }

 static int myvivi_try_fmt_vid_cap(struct file *file, void *priv, struct v4l2_format *f)
 {
     enum v4l2_field field;
     unsigned int max_width, max_height;

     if (f->fmt.pix.pixelformat != V4L2_PIX_FMT_YUYV)
         return -EINVAL;

     field = f->fmt.pix.field;
     if (field == V4L2_FIELD_ANY) {
         field = V4L2_FIELD_INTERLACED;
     }
     else if (V4L2_FIELD_INTERLACED != field) {
         return -EINVAL;
     }
     f->fmt.pix.field = field;

     max_width    = ;
     max_height    = ;

     v4l_bound_align_image(&f->fmt.pix.width, , max_width, ,
                   &f->fmt.pix.height, , max_height, , );
     f->fmt.pix.bytesperline =
         (f->fmt.pix.width * ) >> ;
     f->fmt.pix.sizeimage =
         f->fmt.pix.height * f->fmt.pix.bytesperline;
     f->fmt.pix.colorspace = V4L2_COLORSPACE_SMPTE170M;

     return ;
 }

 static int myvivi_s_fmt_vid_cap(struct file *file, void *priv, struct v4l2_format *f)
 {
     int ret;
     if (videobuf_queue_is_busy(&myvivi_vb_vidq))
         return -EBUSY;

     ret = myvivi_try_fmt_vid_cap(file, priv, f);
     if (ret < )
         return ret;

     memcpy(&myvivi_format, f, sizeof(myvivi_format));

     return ;
 }

 static int myvivi_reqbufs(struct file *file, void *priv, struct v4l2_requestbuffers *p)
 {
     return videobuf_reqbufs(&myvivi_vb_vidq, p);
 }

 static int myvivi_querybuf(struct file *file, void *priv, struct v4l2_buffer *p)
 {
     return videobuf_querybuf(&myvivi_vb_vidq, p);
 }

 static int myvivi_qbuf(struct file *file, void *priv, struct v4l2_buffer *p)
 {
     return videobuf_qbuf(&myvivi_vb_vidq, p);
 }

 static int myvivi_dqbuf(struct file *file, void *priv, struct v4l2_buffer *p)
 {
     return videobuf_dqbuf(&myvivi_vb_vidq, p, file->f_flags & O_NONBLOCK);
 }

 static int myvivi_streamon(struct file *file, void *priv, enum v4l2_buf_type i)
 {
     return videobuf_streamon(&myvivi_vb_vidq);
 }

 static int myvivi_streamoff(struct file *file, void *priv, enum v4l2_buf_type i)
 {
     videobuf_streamoff(&myvivi_vb_vidq);
     return ;
 }

 static const struct v4l2_ioctl_ops myvivi_ioctl_ops = {
     .vidioc_querycap      = myvivi_querycap,
     .vidioc_enum_fmt_vid_cap  = myvivi_enum_fmt_vid_cap,
     .vidioc_g_fmt_vid_cap     = myvivi_g_fmt_vid_cap,
     .vidioc_try_fmt_vid_cap   = myvivi_try_fmt_vid_cap,
     .vidioc_s_fmt_vid_cap     = myvivi_s_fmt_vid_cap,
     .vidioc_reqbufs       = myvivi_reqbufs,
     .vidioc_querybuf      = myvivi_querybuf,
     .vidioc_qbuf          = myvivi_qbuf,
     .vidioc_dqbuf         = myvivi_dqbuf,
     .vidioc_streamon      = myvivi_streamon,
     .vidioc_streamoff     = myvivi_streamoff,
 };

 static void myvivi_release(struct video_device *vdev)
 {
     /* myvivi_exit()中调用了video_device_release()
      * 因此myvivi->release不需要设置为video_device_release
      */
 }

 /* 此函数用于实现其他文件的thread() */
 static void myvivi_timerfunc(unsigned long arg)
 {
     struct videobuf_buffer *vb;
     void *vbuf;

     if (list_empty(&myvivi_list_head))
         goto fail;

     vb = list_first_entry(&myvivi_list_head, struct videobuf_buffer,
                   queue);

     if (!waitqueue_active(&vb->done))
         goto fail;

     /* Fill buffer */
     vbuf = videobuf_to_vmalloc(vb);
     if (!vbuf)
         goto fail;

     /* 由于是虚拟摄像头驱动，所以假装有数据 */
     memset(vbuf, , vb->size);

     vb->field_count++;
     do_gettimeofday(&vb->ts);
     vb->state = VIDEOBUF_DONE;

     /* 把videobuf从队列中删除 */
     list_del(&vb->queue);

     /* 唤醒videobuf->done上的进程 */
     wake_up(&vb->done);

 fail:
     /* 30帧/秒 */
     mod_timer(&myvivi_timer, jiffies + HZ / );
 }

 static int __init myvivi_init(void)
 {
     int ret;

     myvivi = video_device_alloc();

     myvivi->release        = myvivi_release,
     myvivi->fops        = &myvivi_fops;
     myvivi->ioctl_ops     = &myvivi_ioctl_ops;

     /* 初始化spinlock */
     spin_lock_init(&myvivi_slock);
     /* 初始化timer_list */
     init_timer(&myvivi_timer);
     myvivi_timer.function = myvivi_timerfunc;
     /* 初始化list_head */
     INIT_LIST_HEAD(&myvivi_list_head);

     ret = video_register_device(myvivi, VFL_TYPE_GRABBER, -);
     if (ret < ) {
         video_device_release(myvivi);
         return ret;
     }

     return ;
 }

 static void __exit myvivi_exit(void)
 {
     video_unregister_device(myvivi);
     video_device_release(myvivi);
 }

 module_init(myvivi_init);
 module_exit(myvivi_exit);
 MODULE_LICENSE("GPL");

Makefile：

 KERN_DIR = /work/itop4412/tools/linux-3.5

 all:
     make -C $(KERN_DIR) M=`pwd` modules 

 clean:
     make -C $(KERN_DIR) M=`pwd` modules clean
     rm -rf modules.order

 obj-m    += videobuf-vmalloc.o
 obj-m    += myvivi.o

由于是虚拟摄像头，所以源代码中的摄像头参数和数据格式是根据内核规则随意选择的，参数的确定和选取会在下一章进行介绍

本章内容较为混乱，推荐读者自行分析linux/drivers/staging/media/solo6x10/v4l2.c和第八节：数据的获取过程体验各个过程的调用关系