Manual Pages for UNIX Operating System command usage for man devmap_do_ctxmgt

Kernel Functions for Drivers                 devmap_do_ctxmgt(9F)



NAME
     devmap_do_ctxmgt - perform device  context  switching  on  a
     mapping

SYNOPSIS
     #include 
     #include 



     int devmap_do_ctxmgt(devmap_cookie_t dhp, void *pvtp, offset_t off,
          size_t len, uint_t type,
          uint_t rw, int (*devmap_contextmgt)devmap_cookie_t,
          void *, offset_t, size_t, uint_t, uint_t);


INTERFACE LEVEL
     Solaris DDI specific (Solaris DDI).

PARAMETERS
     dhp                   An opaque mapping handle that the sys-
                           tem uses to describe the mapping.


     pvtp                  Driver private mapping data.


     off                   User offset within the logical  device
                           memory at which the access begins.


     len                   Length (in bytes) of the memory  being
                           accessed.


     devmap_contextmgt     The address of  driver  function  that
                           the  system  will call to perform con-
                           text  switching  on  a  mapping.   See
                           devmap_contextmgt(9E) for details.


     type                  Type of access operation.  Provided by
                           devmap_access(9E). Should not be modi-
                           fied.


     rw                    Direction  of  access.   Provided   by
                           devmap_access(9E). Should not be modi-
                           fied.






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Kernel Functions for Drivers                 devmap_do_ctxmgt(9F)



DESCRIPTION
     Device    drivers    call    devmap_do_ctxmgt()    in    the
     devmap_access(9E)  entry  point  to  perform  device context
     switching on a mapping. devmap_do_ctxmgt() passes a  pointer
     to      a     driver     supplied     callback     function,
     devmap_contextmgt(9E), to the system that will  perform  the
     actual  device  context switching.  If devmap_contextmgt(9E)
     is not a valid driver callback  function,  the  system  will
     fail the memory access operation which will result in a SIG-
     SEGV or SIGBUS signal being delivered to the process.


     devmap_do_ctxmgt() performs context switching on the mapping
     object  identified by dhp and pvtp in the range specified by
     off and len. The arguments dhp, pvtp, type, and rw are  pro-
     vided  by  the devmap_access(9E) entry point and must not be
     modified. The range from off to off+len must support context
     switching.


     The system will pass through dhp, pvtp, off,  len, type, and
     rw  to  devmap_contextmgt(9E) in order to perform the actual
     device   context   switching.    The   return   value   from
     devmap_contextmgt(9E)   will   be   returned   directly   to
     devmap_do_ctxmgt().

RETURN VALUES
     0           Successful completion.


     Non-zero    An error occurred.


CONTEXT
     devmap_do_ctxmgt()  must  be  called   from   the   driver's
     devmap_access(9E) entry point.

EXAMPLES
     Example 1 Using devmap_do_ctxmgt in the devmap_access  entry
     point.


     The following shows an example of  using  devmap_do_ctxmgt()
     in the devmap_access(9E) entry point.


       ...
       #define OFF_DO_CTXMGT  0x40000000
       #define OFF_NORMAL     0x40100000
       #define CTXMGT_SIZE    0x100000
       #define NORMAL_SIZE    0x100000




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Kernel Functions for Drivers                 devmap_do_ctxmgt(9F)



       /*
        * Driver devmap_contextmgt(9E) callback function.
        */
       static int
       xx_context_mgt(devmap_cookie_t dhp, void *pvtp, offset_t offset,
           size_t length, uint_t type, uint_t rw)
       {
           ......
           /*
            * see devmap_contextmgt(9E) for an example
            */
       }

       /*
        * Driver devmap_access(9E) entry point
        */
       static int
       xxdevmap_access(devmap_cookie_t dhp, void *pvtp, offset_t off,
           size_t len, uint_t type, uint_t rw)
       {
           offset_t diff;
           int err;

           /*
            * check if off is within the range that supports
            * context management.
            */
           if ((diff = off - OFF_DO_CTXMG) >= 0 && diff < CTXMGT_SIZE) {
               /*
                * calculates the length for context switching
                */
               if ((len + off) > (OFF_DO_CTXMGT + CTXMGT_SIZE))
                   return (-1);
               /*
                * perform context switching
                */
               err = devmap_do_ctxmgt(dhp, pvtp, off, len, type,
                           rw, xx_context_mgt);
           /*
            * check if off is within the range that does normal
            * memory mapping.
            */
           } else if ((diff = off - OFF_NORMAL) >= 0 && diff < NORMAL_SIZE) {
               if ((len + off) > (OFF_NORMAL + NORMAL_SIZE))
                   return (-1);
               err = devmap_default_access(dhp, pvtp, off, len, type, rw);
           } else
               return (-1);

           return (err);
       }




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Kernel Functions for Drivers                 devmap_do_ctxmgt(9F)



SEE ALSO
     devmap_access(9E),                    devmap_contextmgt(9E),
     devmap_default_access(9F)


     Writing Device Drivers

















































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