Kernel Functions for Drivers                    ddimemalloc(9F)



NAME
     ddimemalloc, ddimemfree - allocate and free sequentially
     accessed memory

SYNOPSIS
     #include 
     #include 

     int ddimemalloc(devinfot *dip, ddidmalimt *limits,
          uintt length, uintt flags, caddrt *kaddrp,
          uintt *reallength);


     void ddimemfree(caddrt kaddr);


INTERFACE LEVEL
     These interfaces  are  obsolete.  ddidmamemalloc(9F)  and
     ddidmamemfree(9F) should be used instead.

PARAMETERS
  ddimemalloc()
     dip            A pointer to the device's devinfo structure.


     limits         A pointer to a DMA limits structure for  this
                    device    (see    ddidmalimsparc(9S)    or
                    ddidmalimx86(9S)).  If  this  pointer   is
                    NUL, a default set of DMA limits is assumed.


     length         The length in bytes of  the  desired  alloca-
                    tion.


     flags          The possible flags 1 and 0 are taken to mean,
                    respectively, wait until memory is available,
                    or do not wait.


     kaddrp         On a successful return, *kaddrp points to the
                    allocated memory.


     reallength    The  length  in  bytes  that  was  allocated.
                    Alignment  and padding requirements may cause
                    ddimemalloc() to allocate more memory  than
                    requested in length.


  ddimemfree()




SunOS 5.11          Last change: 04 Apr 2006                    1






Kernel Functions for Drivers                    ddimemalloc(9F)



     kaddr    The memory  returned  from  a  successful  call  to
              ddimemalloc().


DESCRIPTION
     The  ddimemalloc()  function  allocates  memory  for   DMA
     transfers  and  should  be  used if the device is performing
     sequential, unidirectional,  block-sized  and  block-aligned
     transfers to or from memory. This type of access is commonly
     known as streaming access.  The  allocation  will  obey  the
     alignment and padding constraints as specified by the limits
     argument and other limits imposed by the system.


     Note that you must still use DMA resource  allocation  func-
     tions (see ddidmasetup(9F)) to establish DMA resources for
     the memory allocated using ddimemalloc().  ddimemalloc()
     returns  the  actual  size  of  the allocated memory object.
     Because of padding and alignment  requirements,  the  actual
     size    might   be   larger   than   the   requested   size.
     ddidmasetup(9F) requires the actual length.


     In order to make the view of a memory object shared  between
     a  CPU and a DMA device consistent, explicit synchronization
     steps  using  ddidmasync(9F)   or   ddidmafree(9F)   are
     required.


     The ddimemfree() function frees  up  memory  allocated  by
     ddimemalloc().

RETURN VALUES
     The ddimemalloc() function returns:

     DISUCES    Memory successfully allocated.


     DIFAILURE    Allocation failed.


CONTEXT
     The ddimemalloc() function can be called from user, inter-
     rupt,  or  kernel context, except when flags is set to 1, in
     which case it cannot be called from interrupt context.

ATRIBUTES
     See attributes(5) for a description of the following  attri-
     butes:






SunOS 5.11          Last change: 04 Apr 2006                    2






Kernel Functions for Drivers                    ddimemalloc(9F)



     
           ATRIBUTE TYPE               ATRIBUTE VALUE       
    
     Stability Level              Obsolete                    
    


SEE ALSO
     attributes(5),   ddidmafree(9F),    ddidmamemalloc(9F),
     ddidmamemfree(9F),  ddidmasetup(9F),  ddidmasync(9F),
     ddiiopballoc(9F),                   ddidmalimsparc(9S),
     ddidmalimx86(9S), ddidmareq(9S)


     Writing Device Drivers








































SunOS 5.11          Last change: 04 Apr 2006                    3