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ddi_copyout(9f)

ddi_copyout(9F)                Kernel Functions                ddi_copyout(9F)

NAME
       ddi_copyout - copy data from a driver

SYNOPSIS
       #include <sys/types.h>
       #include <sys/ddi.h>
       #include <sys/sunddi.h>

       int ddi_copyout(const void *driverbuf, void *buf, size_t cn, int flags);

INTERFACE LEVEL
       Solaris DDI specific (Solaris DDI).

PARAMETERS
       driverbuf    Source address in the driver from which the data is trans‐
                    ferred.


       buf          Destination address to which the data is transferred.


       cn           Number of bytes to copy.


       flags        Set  of  flag  bits that provide address space information
                    about buf.


DESCRIPTION
       This routine is designed for use in driver ioctl(9E) routines for  dri‐
       vers that support layered ioctls. ddi_copyout() copies data from a dri‐
       ver buffer to a destination address, buf.


       The  flags argument determines the address space information about buf.
       If the FKIOCTL flag is set, this indicates that buf  is  a  kernel  ad‐
       dress,  and ddi_copyout() behaves like bcopy(9F). Otherwise, buf is in‐
       terpreted as a user buffer  address,  and  ddi_copyout()  behaves  like
       copyout(9F).


       Addresses  that  are  word-aligned are moved most efficiently. However,
       the driver developer is not obliged to ensure alignment. This  function
       automatically  finds the most efficient move algorithm according to ad‐
       dress alignment.

RETURN VALUES
       Under normal conditions, 0 is returned to indicate a  successful  copy.
       Otherwise, −1 is returned if one of the following occurs:

           o      Paging  fault;  the  driver tried to access a page of memory
                  for which it did not have read or write access.


           o      Invalid user address, such as a user area or stack area.


           o      Invalid address that  would  have  resulted  in  data  being
                  copied into the user block.


           o      Hardware  fault;  a  hardware  error prevented access to the
                  specified user memory. For example, an uncorrectable  parity
                  or ECC error occurred.


           o      ADI  version  mismatch; the hardware detected a mismatch be‐
                  tween the version specified for the destination address  and
                  the  actual in-memory version. For more information, see the
                  adi(3C) man page.



       If −1 is returned to the caller, driver entry point routines should re‐
       turn EFAULT.

CONTEXT
       ddi_copyout() can be called from user or kernel context only.

EXAMPLES
       Example 1 ddi_copyout() example



       A driver ioctl(9E) routine (line 12) can be used to get or  set  device
       attributes  or  registers.  In  the XX_GETREGS condition (line 25), the
       driver copies the current device register values to another data  area.
       If the specified argument contains an invalid address, an error code is
       returned.


         1  struct device  {        /* layout of physical device registers  */
          2     int      control;    /* physical device control word  */
          3     int      status;     /* physical device status word   */
          4     short    recv_char;  /* receive character from device */
          5     short    xmit_char;  /* transmit character to device  */
          6  };

          7  struct device_state {
          8     volatile struct device *regsp;   /* pointer to device registers */
          9     kmutex_t reg_mutex;              /* protect device registers */
                . . .
         10  };

         11  static void *statep; /* for soft state routines */

         12  xxioctl(dev_t dev, int cmd, int arg, int mode,
         13      cred_t *cred_p, int *rval_p)
         14  {
         15      struct device_state *sp;
         16      volatile struct device *rp;
         17      struct device reg_buf;     /* temporary buffer for registers */
         18      int instance;

         19      instance = getminor(dev);
         20      sp = ddi_get_soft_state(statep, instance);
         21      if (sp == NULL)
         22          return (ENXIO);
         23      rp = sp->regsp;
                 . . .
         24      switch (cmd)  {

         25      case XX_GETREGS:   /* copy registers to arg */
         26            mutex_enter(&sp->reg_mutex);
         27            /*
         28             * Copy data from device registers to
         29             * temporary device register buffer
         30             * e.g. reg_buf.control = rp->control;
         31             */
         32            mutex_exit(&sp->reg_mutex);
         33            if (ddi_copyout(&reg_buf, arg,
         34                sizeof (struct device), mode) != 0) {
         35                    return (EFAULT);
         36            }

         37            break;
         38      }
         39  }


SEE ALSO
       ioctl(9E),    bcopy(9F),   copyin(9F),   copyout(9F),   ddi_copyin(9F),
       uiomove(9F)


       Writing Device Drivers in Oracle Solaris 11.4

NOTES
       The value of the flags  argument  to  ddi_copyout()  should  be  passed
       through directly from the mode argument of ioctl() untranslated.


       Driver defined locks should not be held across calls to this function.


       ddi_copyout() should not be used from a streams driver. For more infor‐
       mation, see M_COPYIN and M_COPYOUT in STREAMS Programming Guide.

Oracle Solaris 11.4               30 Sep 2015                  ddi_copyout(9F)
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