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NAME
     ddi_mapdev_intercept,   ddi_mapdev_nointercept   -   control
     driver notification of user accesses

SYNOPSIS
     #include <sys/sunddi.h>

     int ddi_mapdev_intercept(ddi_mapdev_handle_t  handle,  off_t
     offset, off_t len);

     int ddi_mapdev_nointercept(ddi_mapdev_handle_t handle, off_t
     offset, off_t len);

INTERFACE LEVEL
     Solaris DDI specific (Solaris DDI).

PARAMETERS
     handle
           An opaque pointer to a device mapping handle.

     offset
           An offset in bytes within device memory.

     len   Length in bytes.

DESCRIPTION
     Future releases of Solaris will provide these functions  for
     binary   and  source  compatibility.  However, for increased
     functionality, use   devmap_load(9F)  or   devmap_unload(9F)
     instead.   See   devmap_load(9F)  and  devmap_unload(9F) for
     details.

     The   ddi_mapdev_intercept()  and   ddi_mapdev_nointercept()
     functions  control  whether  or  not user accesses to device
     mappings created by ddi_mapdev(9F) in  the  specified  range
     will  generate  calls to the  mapdev_access(9E) entry point.
     ddi_mapdev_intercept() tells the  system  to  intercept  the
     user  access and notify the driver to invalidate the mapping
     translations. ddi_mapdev_nointercept() tells the  system  to
     not  intercept  the  user  access and allow it to proceed by
     validating the mapping translations.

     For both routines, the range to be affected  is  defined  by
     the   offset  and  len arguments. Requests affect the entire
     page containing the offset and all pages up to and including
     the  page  containing the last byte as indicated by offset +
     len.

     Supplying a value of  0 for the  len  argument  affects  all
     addresses from the offset to the end of the mapping. Supply-
     ing a value of 0 for the offset argument and a  value  of  0
     for len argument affect all addresses in the mapping.
     To manage a device  context,  a  device  driver  would  call
     ddi_mapdev_intercept()  on  the context about to be switched
     out, switch contexts, and then call ddi_mapdev_nointercept()
     on the context switched in.

RETURN VALUES
     ddi_mapdev_intercept() and  ddi_mapdev_nointercept()  return
     the following values:

     0     Successful completion.

     Non-zero
           An error occurred.

EXAMPLES
     Example 1: managing a device context that  is  one  page  in
     length

     The following shows an example of managing a device  context
     that is one page in length.

     ddi_mapdev_handle_t cur_hdl;
     static int
     xxmapdev_access(ddi_mapdev_handle_t handle, void *devprivate,
         off_t offset)
     {
          int err;
          /* enable access callbacks for the current mapping */
          if (cur_hdl != NULL) {
               if ((err = ddi_mapdev_intercept(cur_hdl, offset, 0)) != 0)
                    return (err);
          }
          /* Switch device context - device dependent*/
          ...
          /* Make handle the new current mapping */
          cur_hdl = handle;
          /*
           * Disable callbacks and complete the access for the
           * mapping that generated this callback.
           */
          return (ddi_mapdev_nointercept(handle, offset, 0));
     }

CONTEXT
     These routines can be called from  user  or  kernel  context
     only.

SEE ALSO
     mapdev_access(9E), ddi_mapdev(9F)

     Writing Device Drivers

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