awrite(9E)

NAME

     awrite - asynchronous write to a device

SYNOPSIS

     #include <sys/uio.h>
     #include <sys/aio_req.h>
     #include <sys/cred.h>
     #include <sys/ddi.h>
     #include <sys/sunddi.h>

     intprefixawrite(dev_t dev, struct aio_req *aio_reqp,  cred_t
     *cred_p);

INTERFACE LEVEL

     Solaris DDI specific (Solaris  DDI).  This  entry  point  is
     optional.  Drivers  that  do  not support an  awrite() entry
     point should use  nodev(9F)

PARAMETERS

     dev   Device number.

     aio_reqp
           Pointer to the  aio_req(9S) structure  that  describes
           where the data is stored.

     cred_p
           Pointer to the  credential structure.

DESCRIPTION

     The driver's awrite() routine is called to perform an  asyn-
     chronous  write.  getminor(9F)  can  be  used to  access the
     minor number component of the dev argument. awrite() may use
     the  credential structure pointed to by  cred_p to check for
     superuser access by  calling   drv_priv(9F).  The   awrite()
     routine  may also examine the  uio(9S) structure through the
     aio_req structure pointer,   aio_reqp.  awrite()  must  call
     aphysio(9F)  with  the  aio_req pointer and a pointer to the
     driver's strategy(9E) routine.

     No fields of the uio(9S) structure pointed  to  by  aio_req,
     other  than  uio_offset  or uio_loffset, may be modified for
     non-seekable devices.

RETURN VALUES

     The  awrite() routine should return   0 for success, or  the
     appropriate error number.

CONTEXT

     This function is called from user context only.

EXAMPLES

     Example 1: Using the awrite routine:

     The following is an example of an  awrite() routine:

     static int
     xxawrite(dev_t dev, struct aio_req *aio, cred_t *cred_p)
     {
             int instance;
             struct xxstate *xsp;

             instance = getminor(dev);
             xsp = ddi_get_soft_state(statep, instance);
             /*Verify soft state structure has been allocated */
             if (xsp == NULL)
                      return (ENXIO);
             return (aphysio(xxstrategy, anocancel, dev, B_WRITE, xxminphys, aio));
     }

SEE ALSO

     write(2), aiowrite(3AIO), aread(9E), read(9E), strategy(9E),
     write(9E),            anocancel(9F),            aphysio(9F),
     ddi_get_soft_state(9F),     drv_priv(9F),      getminor(9F),
     minphys(9F), nodev(9F), aio_req(9S), cb_ops(9S), uio(9S)

     Writing Device Drivers

BUGS

     There is no way other than calling aphysio(9F) to accomplish
     an asynchronous write.