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<?xml version="1.0" encoding="koi8-r" standalone="no"?>
<!--
     The FreeBSD Russian Documentation Project

     $FreeBSD$
     $FreeBSDru: frdp/doc/ru_RU.KOI8-R/books/developers-handbook/driverbasics/chapter.sgml,v 1.1 2001/01/10 08:45:03 andy Exp $

     Original revision: 1.3
-->

<chapter id="driverbasics">
  <title>    FreeBSD</title>

  <para>     (Murray Stokely)   
    ,    intro(4),  
     (Joerg Wunsch).</para>

  <sect1>
    <title></title>

    <para>        
        FreeBSD.       
         ,   ,   ,
      ,  ,      
      .      
       ,   .   
        -,     
         ,   -
       .     
              
            `kld'.</para>

    <para>   Unix-   
         (device-nodes),   
       .        
         <filename>/dev</filename>.    devfs
          FreeBSD,    
             
       .       
         <command>MAKEDEV</command>.</para>

    <para>        ;
          .</para>
  </sect1>

  <sect1>
    <title>    - KLD</title>

    <para> kld    
            .  
           
             
       .</para>

    <para>    kld   
      :

      <itemizedlist>
        <listitem>
          <simpara>
            <command>kldload</command> -    
          </simpara>
        </listitem>

        <listitem>
          <simpara>
            <command>kldunload</command> -   
          </simpara>
        </listitem>

        <listitem>
          <simpara>
            <command>kldstat</command> -     
             
          </simpara>
        </listitem>
      </itemizedlist>
    </para>

    <para>  </para>

    <programlisting>
/*
 * KLD Skeleton
 * Inspired by Andrew Reiter's Daemonnews article
 */

#include &lt;sys/types.h&gt;
#include &lt;sys/module.h&gt;
#include &lt;sys/systm.h&gt;  /* uprintf */
#include &lt;sys/errno.h&gt;
#include &lt;sys/param.h&gt;  /* defines used in kernel.h */
#include &lt;sys/kernel.h&gt; /* types used in module initialization */

/*
 * Load handler that deals with the loading and unloading of a KLD.
 */

static int
skel_loader(struct module *m, int what, void *arg)
{
  int err = 0;

  switch (what) {
  case MOD_LOAD:                /* kldload */
    uprintf("Skeleton KLD loaded.\n");
    break;
  case MOD_UNLOAD:
    uprintf("Skeleton KLD unloaded.\n");
    break;
  default:
    err = EINVAL;
    break;
  }
  return(err);
}

/* Declare this module to the rest of the kernel */

DECLARE_MODULE(skeleton, skel_loader, SI_SUB_KLD, SI_ORDER_ANY);
    </programlisting>

    <sect2>
      <title>Makefile</title>

      <para> FreeBSD      make-, 
               
         .</para>

      <programlisting>
SRCS=skeleton.c
KMOD=skeleton

.include &lt;bsd.kmod.mk&gt;
      </programlisting>

      <para>   <command>make</command>   make-
            <filename>skeleton.ko</filename>, 
            , :

        <screen>
&prompt.root kldload -v ./skeleton.ko
        </screen>
      </para>
    </sect2>
  </sect1>

  <sect1>
    <title>   </title>

    <para>Unix        
        .     
       ,       
        .  
      <command>/dev/MAKEDEV</command>     
       ,       
      ,       
           <command>mknod</command>.</para>

    <sect2>
      <title>   </title>

      <para>     <command>mknod</command>
           .      
         ,  ,     
         .</para>
    </sect2>

    <sect2>
      <title>  </title>

      <para>  , devfs,   
               
         .      
                
          .  Devfs    
        ,      .</para>
    </sect2>
  </sect1>

  <sect1>
    <title> </title>

    <para>      
         .      
              
        .</para>

    <para>    -   
      ,     ,     
           .</para>

    <programlisting>
/*
 * Simple `echo' pseudo-device KLD
 *
 * Murray Stokely
 */

#define MIN(a,b) (((a) < (b)) ? (a) : (b))

#include &lt;sys/types.h&gt;
#include &lt;sys/module.h&gt;
#include &lt;sys/systm.h&gt; /* uprintf */
#include &lt;sys/errno.h&gt;
#include &lt;sys/param.h&gt;  /* defines used in kernel.h */
#include &lt;sys/kernel.h&gt; /* types used in module initialization */
#include &lt;sys/conf.h&gt;   /* cdevsw struct */
#include &lt;sys/uio.h&gt;    /* uio struct */
#include &lt;sys/malloc.h&gt;

#define BUFFERSIZE 256

/* Function prototypes */
d_open_t      echo_open;
d_close_t     echo_close;
d_read_t      echo_read;
d_write_t     echo_write;

/* Character device entry points */
static struct cdevsw echo_cdevsw = {
  echo_open,
  echo_close,
  echo_read,
  echo_write,
  noioctl,
  nopoll,
  nommap,
  nostrategy,
  "echo",
  33,                   /* reserved for lkms - /usr/src/sys/conf/majors */
  nodump,
  nopsize,
  D_TTY,
  -1
};

typedef struct s_echo {
  char msg[BUFFERSIZE];
  int len;
} t_echo;

/* vars */
static dev_t sdev;
static int len;
static int count;
static t_echo *echomsg;

MALLOC_DECLARE(M_ECHOBUF);
MALLOC_DEFINE(M_ECHOBUF, "echobuffer", "buffer for echo module");

/*
 * This function acts is called by the kld[un]load(2) system calls to
 * determine what actions to take when a module is loaded or unloaded.
 */

static int
echo_loader(struct module *m, int what, void *arg)
{
  int err = 0;

  switch (what) {
  case MOD_LOAD:                /* kldload */
    sdev = make_dev(<literal>&</literal>echo_cdevsw,
                    0,
                    UID_ROOT,
                    GID_WHEEL,
                    0600,
                    "echo");
    /* kmalloc memory for use by this driver */
    /*    malloc(256,M_ECHOBUF,M_WAITOK); */
    MALLOC(echomsg, t_echo *, sizeof(t_echo), M_ECHOBUF, M_WAITOK);
    printf("Echo device loaded.\n");
    break;
  case MOD_UNLOAD:
    destroy_dev(sdev);
    FREE(echomsg,M_ECHOBUF);
    printf("Echo device unloaded.\n");
    break;
  default:
    err = EINVAL;
    break;
  }
  return(err);
}

int
echo_open(dev_t dev, int oflags, int devtype, struct proc *p)
{
  int err = 0;

  uprintf("Opened device \"echo\" successfully.\n");
  return(err);
}

int
echo_close(dev_t dev, int fflag, int devtype, struct proc *p)
{
  uprintf("Closing device \"echo.\"\n");
  return(0);
}

/*
 * The read function just takes the buf that was saved via
 * echo_write() and returns it to userland for accessing.
 * uio(9)
 */

int
echo_read(dev_t dev, struct uio *uio, int ioflag)
{
  int err = 0;
  int amt;

  /* How big is this read operation?  Either as big as the user wants,
     or as big as the remaining data */
  amt = MIN(uio->uio_resid, (echomsg->len - uio->uio_offset > 0) ? echomsg->len - uio->uio_offset : 0);
  if ((err = uiomove(echomsg->msg + uio->uio_offset,amt,uio)) != 0) {
    uprintf("uiomove failed!\n");
  }

  return err;
}

/*
 * echo_write takes in a character string and saves it
 * to buf for later accessing.
 */

int
echo_write(dev_t dev, struct uio *uio, int ioflag)
{
  int err = 0;

  /* Copy the string in from user memory to kernel memory */
  err = copyin(uio->uio_iov->iov_base, echomsg->msg, MIN(uio->uio_iov->iov_len,BUFFERSIZE));

  /* Now we need to null terminate */
  *(echomsg->msg + MIN(uio->uio_iov->iov_len,BUFFERSIZE)) = 0;
  /* Record the length */
  echomsg->len = MIN(uio->uio_iov->iov_len,BUFFERSIZE);

  if (err != 0) {
    uprintf("Write failed: bad address!\n");
  }

  count++;
  return(err);
}

DEV_MODULE(echo,echo_loader,NULL);
    </programlisting>

    <para> ,    ,    
             , 
      :</para>

    <screen>
&prompt.root mknod /dev/echo c 33 0
    </screen>

    <para>   ,    
      :</para>

    <screen>
&prompt.root echo -n "Test Data" > /dev/echo
&prompt.root cat /dev/echo
Test Data
    </screen>

    <para> ,   , 
        ..</para>

    <para>  
      <itemizedlist>
        <listitem>
          <simpara><ulink
            url="http://www.daemonnews.org/200010/blueprints.html">
                 
            (KLD)</ulink> - <ulink
            url="http://www.daemonnews.org">Daemonnews</ulink>
             2000
          </simpara>
        </listitem>

        <listitem>
          <simpara><ulink
            url="http://www.daemonnews.org/200007/newbus-intro.html">
                 NEWBUS</ulink> - <ulink
            url="http://www.daemonnews.org">Daemonnews</ulink>  2000
          </simpara>
        </listitem>
      </itemizedlist>
    </para>
  </sect1>

  <sect1>
    <title> </title>

    <para>         
        .       , 
       ,     open();   
              
      socket(2).</para>

    <para>     ifnet(), 
      loopback,     (Bill Paul),  
      ..</para>
  </sect1>
</chapter>