linux man page for ddi_mem_alloc

ddi_mem_alloc(9F)					   Kernel Functions for Drivers 					 ddi_mem_alloc(9F)

NAME

       ddi_mem_alloc, ddi_mem_free - allocate and free sequentially accessed memory

SYNOPSIS

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

       int ddi_mem_alloc(dev_info_t *dip, ddi_dma_lim_t *limits, uint_t length, uint_t flags, caddr_t *kaddrp, uint_t *real_length);

       void ddi_mem_free(caddr_t kaddr);

INTERFACE LEVEL

       These interfaces are obsolete. ddi_dma_mem_alloc(9F) and ddi_dma_mem_free(9F) should be used instead.

PARAMETERS

   ddi_mem_alloc()
       dip	       A pointer to the device's dev_info structure.

       limits	       A  pointer to a DMA limits structure for this device (see ddi_dma_lim_sparc(9S) or ddi_dma_lim_x86(9S)). If this pointer is
		       NULL, a default set of DMA limits is assumed.

       length	       The length in bytes of the desired allocation.

       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.

       real_length     The length in bytes that was allocated. Alignment and padding requirements may cause ddi_mem_alloc() to allocate more  mem-
		       ory than requested in length.

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

DESCRIPTION

       ddi_mem_alloc()	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 functions (see ddi_dma_setup(9F)) to establish DMA resources for the memory allocated
       using ddi_mem_alloc(). ddi_mem_alloc() returns the actual size of the allocated memory object.  Because of padding and  alignment  require-
       ments, the actual size might be larger than the	requested size. ddi_dma_setup(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
       ddi_dma_sync(9F) or ddi_dma_free(9F) are required.

       ddi_mem_free() frees up memory allocated by ddi_mem_alloc().

RETURN VALUES

       ddi_mem_alloc() returns:

       DDI_SUCCESS     Memory successfully allocated.

       DDI_FAILURE     Allocation failed.

CONTEXT

       ddi_mem_alloc() can be called from user or interrupt context, except when  flags is set to 1, in which case it can be called from user con-
       text only.

ATTRIBUTES

       See attributes(5) for a description of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Stability Level 	     |Obsolete			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       attributes(5),  ddi_dma_free(9F),  ddi_dma_mem_alloc(9F),  ddi_dma_mem_free(9F),  ddi_dma_setup(9F),  ddi_dma_sync(9F), ddi_iopb_alloc(9F),
       ddi_dma_lim_sparc(9S), ddi_dma_lim_x86(9S), ddi_dma_req(9S)

       Writing Device Drivers

SunOS 5.10							    27 Sep 2002 						 ddi_mem_alloc(9F)