bus_dmamap_load_mbuf man page on NetBSD

Man page or keyword search:  
man Server   9087 pages
apropos Keyword Search (all sections)
Output format
NetBSD logo
[printable version]

BUS_DMA(9)		 BSD Kernel Developer's Manual		    BUS_DMA(9)

NAME
     bus_dma, bus_dmamap_create, bus_dmamap_destroy, bus_dmamap_load,
     bus_dmamap_load_mbuf, bus_dmamap_load_uio, bus_dmamap_load_raw,
     bus_dmamap_unload, bus_dmamap_sync, bus_dmamem_alloc, bus_dmamem_free,
     bus_dmamem_map, bus_dmamem_unmap, bus_dmamem_mmap, bus_dmatag_subregion,
     bus_dmatag_destroy — Bus and Machine Independent DMA Mapping Interface

SYNOPSIS
     #include <sys/bus.h>

     int
     bus_dmamap_create(bus_dma_tag_t tag, bus_size_t size, int nsegments,
	 bus_size_t maxsegsz, bus_size_t boundary, int flags,
	 bus_dmamap_t *dmamp);

     void
     bus_dmamap_destroy(bus_dma_tag_t tag, bus_dmamap_t dmam);

     int
     bus_dmamap_load(bus_dma_tag_t tag, bus_dmamap_t dmam, void *buf,
	 bus_size_t buflen, struct lwp *l, int flags);

     int
     bus_dmamap_load_mbuf(bus_dma_tag_t tag, bus_dmamap_t dmam,
	 struct mbuf *chain, int flags);

     int
     bus_dmamap_load_uio(bus_dma_tag_t tag, bus_dmamap_t dmam,
	 struct uio *uio, int flags);

     int
     bus_dmamap_load_raw(bus_dma_tag_t tag, bus_dmamap_t dmam,
	 bus_dma_segment_t *segs, int nsegs, bus_size_t size, int flags);

     void
     bus_dmamap_unload(bus_dma_tag_t tag, bus_dmamap_t dmam);

     void
     bus_dmamap_sync(bus_dma_tag_t tag, bus_dmamap_t dmam, bus_addr_t offset,
	 bus_size_t len, int ops);

     int
     bus_dmamem_alloc(bus_dma_tag_t tag, bus_size_t size,
	 bus_size_t alignment, bus_size_t boundary, bus_dma_segment_t *segs,
	 int nsegs, int *rsegs, int flags);

     void
     bus_dmamem_free(bus_dma_tag_t tag, bus_dma_segment_t *segs, int nsegs);

     int
     bus_dmamem_map(bus_dma_tag_t tag, bus_dma_segment_t *segs, int nsegs,
	 size_t size, void **kvap, int flags);

     void
     bus_dmamem_unmap(bus_dma_tag_t tag, void *kva, size_t size);

     paddr_t
     bus_dmamem_mmap(bus_dma_tag_t tag, bus_dma_segment_t *segs, int nsegs,
	 off_t off, int prot, int flags);

     int
     bus_dmatag_subregion(bus_dma_tag_t tag, bus_addr_t min_addr,
	 bus_addr_t max_addr, bus_dma_tag_t *newtag, int flags);

     void
     bus_dmatag_destroy(bus_dma_tag_t tag);

DESCRIPTION
     Provide a bus- and machine-independent "DMA mapping interface."

IMPLEMENTATION NOTES
     All data types and constants will be defined by the port-specific header
     <machine/bus_defs.h>.  All functions will be defined by the port-specific
     header <machine/bus_funcs.h>.  Note that this document assumes the exis‐
     tence of types already defined by the current "bus.h" interface.

     Unless otherwise noted, all function calls in this interface may be
     defined as cpp(1) macros.

DATA TYPES
     Individual implementations may name these structures whatever they wish,
     providing that the external representations are:

     bus_dma_tag_t
	      A machine-dependent opaque type describing the implementation of
	      DMA for a given bus.

     bus_dma_segment_t
	      A structure with at least the following members:

		      bus_addr_t      ds_addr;
		      bus_size_t      ds_len;

	      The structure may have machine-dependent members and arbitrary
	      layout.  The values in ds_addr and ds_len are suitable for pro‐
	      gramming into DMA controller address and length registers.

     bus_dmamap_t
	      A pointer to a structure with at least the following members:

		      bus_size_t      dm_maxsegsz;
		      bus_size_t      dm_mapsize;
		      int	      dm_nsegs;
		      bus_dma_segment_t *dm_segs;

	      The structure may have machine-dependent members and arbitrary
	      layout.  The dm_maxsegsz member indicates the maximum number of
	      bytes that may be transferred by any given DMA segment.  The
	      dm_mapsize member indicates the size of the mapping.  A value of
	      0 indicates the mapping is invalid.  The dm_segs member may be
	      an array of segments or a pointer to an array of segments.  The
	      dm_nsegs member indicates the number of segments in dm_segs.

FUNCTIONS
     bus_dmamap_create(tag, size, nsegments, maxsegsz, boundary, flags, dmamp)
	      Allocates a DMA handle and initializes it according to the
	      parameters provided.  Arguments are as follows:
	      tag	 This is the bus_dma_tag_t passed down from the parent
			 driver via <bus>_attach_args.
	      size	 This is the maximum DMA transfer that can be mapped
			 by the handle.
	      nsegments	 Number of segments the device can support in a single
			 DMA transaction.  This may be the number of scatter-
			 gather descriptors supported by the device.
	      maxsegsz	 The maximum number of bytes that may be transferred
			 by any given DMA segment and will be assigned to the
			 dm_maxsegsz member.
	      boundary	 Some DMA controllers are not able to transfer data
			 that crosses a particular boundary.  This argument
			 allows this boundary to be specified.	The boundary
			 lines begin at 0, and occur every boundary bytes.
			 Mappings may begin on a boundary line but may not end
			 on or cross a boundary line.  If no boundary condi‐
			 tion needs to be observed, a boundary argument of 0
			 should be used.
	      flags	 Flags are defined as follows:
			 BUS_DMA_WAITOK	   It is safe to wait (sleep) for
					   resources during this call.
			 BUS_DMA_NOWAIT	   It is not safe to wait (sleep) for
					   resources during this call.
			 BUS_DMA_ALLOCNOW  Perform any resource allocation
					   this handle may need now.  If this
					   is not specified, the allocation
					   may be deferred to
					   bus_dmamap_load().  If this flag is
					   specified, bus_dmamap_load() will
					   not block on resource allocation.
			 BUS_DMA_BUS[1-4]  These flags are placeholders, and
					   may be used by busses to provide
					   bus-dependent functionality.
	      dmamp	 This is a pointer to a bus_dmamap_t.  A DMA map will
			 be allocated and pointed to by dmamp upon successful
			 completion of this routine.  dmamp is undefined if
			 this routine fails.

	      Behavior is not defined if invalid arguments are passed to
	      bus_dmamap_create().

	      Returns 0 on success, or an error code to indicate mode of fail‐
	      ure.

     bus_dmamap_destroy(tag, dmam)
	      Frees all resources associated with a given DMA handle.  Argu‐
	      ments are as follows:
	      tag   This is the bus_dma_tag_t passed down from the parent
		    driver via <bus>_attach_args.
	      dmam  The DMA handle to destroy.

	      In the event that the DMA handle contains a valid mapping, the
	      mapping will be unloaded via the same mechanism used by
	      bus_dmamap_unload().

	      Behavior is not defined if invalid arguments are passed to
	      bus_dmamap_destroy().

	      If given valid arguments, bus_dmamap_destroy() always succeeds.

     bus_dmamap_load(tag, dmam, buf, buflen, l, flags)
	      Loads a DMA handle with mappings for a DMA transfer.  It assumes
	      that all pages involved in a DMA transfer are wired.  Arguments
	      are as follows:
	      tag     This is the bus_dma_tag_t passed down from the parent
		      driver via <bus>_attach_args.
	      dmam    The DMA handle with which to map the transfer.
	      buf     The buffer to be used for the DMA transfer.
	      buflen  The size of the buffer.
	      l	      Used to indicate the address space in which the buffer
		      is located.  If NULL, the buffer is assumed to be in
		      kernel space.  Otherwise, the buffer is assumed to be in
		      lwp l's address space.
	      flags   are defined as follows:
		      BUS_DMA_WAITOK	 It is safe to wait (sleep) for
					 resources during this call.
		      BUS_DMA_NOWAIT	 It is not safe to wait (sleep) for
					 resources during this call.
		      BUS_DMA_STREAMING	 By default, the bus_dma API assumes
					 that there is coherency between mem‐
					 ory and the device performing the DMA
					 transaction.  Some platforms, how‐
					 ever, have special hardware, such as
					 an “I/O cache”, which may improve
					 performance of some types of DMA
					 transactions, but which break the
					 assumption that there is coherency
					 between memory and the device per‐
					 forming the DMA transaction.  This
					 flag allows the use of this special
					 hardware, provided that the device is
					 doing sequential, unidirectional
					 transfers which conform to certain
					 alignment and size constraints
					 defined by the platform.  If the
					 platform does not support the fea‐
					 ture, or if the buffer being loaded
					 into the DMA map does not conform to
					 the constraints required for use of
					 the feature, then this flag will be
					 silently ignored.  Also refer to the
					 use of this flag with the
					 bus_dmamem_alloc() function.
		      BUS_DMA_READ	 This is a hint to the machine-depen‐
					 dent back-end that indicates the map‐
					 ping will be used only for a device
					 -> memory transaction.	 The back-end
					 may perform optimizations based on
					 this information.
		      BUS_DMA_WRITE	 This is a hint to the machine-depen‐
					 dent back-end that indicates the map‐
					 ping will be used only for a memory
					 -> device transaction.	 The back-end
					 may perform optimizations based on
					 this information.
		      BUS_DMA_BUS[1-4]	 These flags are placeholders, and may
					 be used by busses to provide bus-
					 dependent functionality.

	      As noted above, if a DMA handle is created with
	      BUS_DMA_ALLOCNOW, bus_dmamap_load() will never block.

	      If a call to bus_dmamap_load() fails, the mapping in the DMA
	      handle will be invalid.  It is the responsibility of the caller
	      to clean up any inconsistent device state resulting from incom‐
	      plete iteration through the uio.

	      Behavior is not defined if invalid arguments are passed to
	      bus_dmamap_load().

	      Returns 0 on success, or an error code to indicate mode of fail‐
	      ure.  Possible error codes include the following:

	      EFBIG
		    Too many segments.
	      EINVAL
		    buflen is too large for the DMA map.
	      ENOMEM
		    Could not allocate memory for, e.g., a bounce buffer.

     bus_dmamap_load_mbuf(tag, dmam, chain, flags)
	      This is a variation of bus_dmamap_load() which maps mbuf chains
	      for DMA transfers.  Mbuf chains are assumed to be in kernel vir‐
	      tual address space.

     bus_dmamap_load_uio(tag, dmam, uio, flags)
	      This is a variation of bus_dmamap_load() which maps buffers
	      pointed to by uio for DMA transfers.  Determination if the buf‐
	      fers are in user or kernel virtual address space is done inter‐
	      nally, according to uio->uio_vmspace.  See uiomove(9) for
	      details of the uio structure.

     bus_dmamap_load_raw(tag, dmam, segs, nsegs, size, flags)
	      This is a variation of bus_dmamap_load() which maps buffers
	      allocated by bus_dmamem_alloc() (see below).  The segs argument
	      is an array of bus_dma_segment_t's filled in by
	      bus_dmamem_alloc().  The nsegs argument is the number of seg‐
	      ments in the array.  The size argument is the size of the DMA
	      transfer.

     bus_dmamap_unload(tag, dmam)
	      Deletes the mappings for a given DMA handle.  Arguments are as
	      follows:
	      tag   This is the bus_dma_tag_t passed down from the parent
		    driver via <bus>_attach_args.
	      dmam  The DMA handle containing the mappings which are to be
		    deleted.

	      If the DMA handle was created with BUS_DMA_ALLOCNOW,
	      bus_dmamap_unload() will not free the corresponding resources
	      which were allocated by bus_dmamap_create().  This is to ensure
	      that bus_dmamap_load() will never block on resources if the han‐
	      dle was created with BUS_DMA_ALLOCNOW.

	      bus_dmamap_unload() will not perform any implicit synchroniza‐
	      tion of DMA buffers.  This must be done explicitly by
	      bus_dmamap_sync().

	      bus_dmamap_unload() will restore the dm_maxsegsz member to its
	      initial value assigned by bus_dmamap_create().

	      Behavior is not defined if invalid arguments are passed to
	      bus_dmamap_unload().

	      If given valid arguments, bus_dmamap_unload() always succeeds.

     bus_dmamap_sync(tag, dmam, offset, len, ops)
	      Performs pre- and post-DMA operation cache and/or buffer syn‐
	      chronization.  Arguments are as follows:
	      tag     This is the bus_dma_tag_t passed down from the parent
		      driver via <bus>_attach_args.
	      dmam    The DMA mapping to be synchronized.
	      offset  The offset into the DMA mapping to synchronize.
	      len     The length of the mapping from offset to synchronize.
	      ops     One or more synchronization operation to perform.	 The
		      following DMA synchronization operations are defined:
		      BUS_DMASYNC_PREREAD    Perform any pre-read DMA cache
					     and/or bounce operations.
		      BUS_DMASYNC_POSTREAD   Perform any post-read DMA cache
					     and/or bounce operations.
		      BUS_DMASYNC_PREWRITE   Perform any pre-write DMA cache
					     and/or bounce operations.
		      BUS_DMASYNC_POSTWRITE  Perform any post-write DMA cache
					     and/or bounce operations.

		      More than one operation may performed in a given syn‐
		      chronization call.  Mixing of PRE and POST operations is
		      not allowed, and behavior is undefined if this is
		      attempted.

	      Synchronization operations are expressed from the perspective of
	      the host RAM, e.g., a device -> memory operation is a READ and a
	      memory -> device operation is a WRITE.

	      bus_dmamap_sync() may consult state kept within the DMA map to
	      determine if the memory is mapped in a DMA coherent fashion.  If
	      so, bus_dmamap_sync() may elect to skip certain expensive opera‐
	      tions, such as flushing of the data cache.  See bus_dmamem_map()
	      for more information on this subject.

	      On platforms which implement a weak memory access ordering
	      model, bus_dmamap_sync() will always cause the appropriate mem‐
	      ory barriers to be issued.

	      This function exists to ensure that the host and the device have
	      a consistent view of a range of DMA memory, before and after a
	      DMA operation.

	      An example of using bus_dmamap_sync(), involving multiple read-
	      write use of a single mapping might look like this:

	      bus_dmamap_load(...);

	      while (not done) {
		      /* invalidate soon-to-be-stale cache blocks */
		      bus_dmamap_sync(..., BUS_DMASYNC_PREREAD);

		      [ do read DMA ]

		      /* copy from bounce */
		      bus_dmamap_sync(..., BUS_DMASYNC_POSTREAD);

		      /* read data now in driver-provided buffer */

		      [ computation ]

		      /* data to be written now in driver-provided buffer */

		      /* flush write buffers and writeback, copy to bounce */
		      bus_dmamap_sync(..., BUS_DMASYNC_PREWRITE);

		      [ do write DMA ]

		      /* probably a no-op, but provided for consistency */
		      bus_dmamap_sync(..., BUS_DMASYNC_POSTWRITE);
	      }

	      bus_dmamap_unload(...);

	      This function must be called to synchronize DMA buffers before
	      and after a DMA operation.  Other bus_dma functions can not be
	      relied on to do this synchronization implicitly.	If DMA read
	      and write operations are not preceded and followed by the appro‐
	      priate synchronization operations, behavior is undefined.

	      Behavior is not defined if invalid arguments are passed to
	      bus_dmamap_sync().

	      If given valid arguments, bus_dmamap_sync() always succeeds.

     bus_dmamem_alloc(tag, size, alignment, boundary, segs, ...)
	      Allocates memory that is "DMA safe" for the bus corresponding to
	      the given tag.

	      The mapping of this memory is machine-dependent (or "opaque");
	      machine-independent code is not to assume that the addresses
	      returned are valid in kernel virtual address space, or that the
	      addresses returned are system physical addresses.	 The address
	      value returned as part of segs can thus not be used to program
	      DMA controller address registers.	 Only the values in the
	      dm_segs array of a successfully loaded DMA map (using
	      bus_dmamap_load()) can be used for this purpose.

	      Allocations will always be rounded to the hardware page size.
	      Callers may wish to take advantage of this, and cluster alloca‐
	      tion of small data structures.  Arguments are as follows:
	      tag	 This is the bus_dma_tag_t passed down from the parent
			 driver via <bus>_attach_args.
	      size	 The amount of memory to allocate.
	      alignment	 Each segment in the allocated memory will be aligned
			 to this value.	 If the alignment is less than a hard‐
			 ware page size, it will be rounded up to the hardware
			 page size.  This value must be a power of two.
	      boundary	 Each segment in the allocated memory must not cross
			 this boundary (relative to zero).  This value must be
			 a power of two.  A boundary value less than the size
			 of the allocation is invalid.
	      segs	 An array of bus_dma_segment_t's, filled in as memory
			 is allocated, representing the opaque addresses of
			 the memory chunks.
	      nsegs	 Specifies the number of segments in segs, and this is
			 the maximum number of segments that the allocated
			 memory may contain.
	      rsegs	 Used to return the actual number of segments the mem‐
			 ory contains.
	      flags	 Flags are defined as follows:
			 BUS_DMA_WAITOK	    It is safe to wait (sleep) for
					    resources during this call.
			 BUS_DMA_NOWAIT	    It is not safe to wait (sleep) for
					    resources during this call.
			 BUS_DMA_STREAMING  Adjusts, if necessary, the size,
					    alignment, and boundary constrains
					    to conform to the platform-depen‐
					    dent requirements for the use of
					    the BUS_DMA_STREAMING flag with
					    the bus_dmamap_load() function.
					    If the platform does not support
					    the BUS_DMA_STREAMING feature, or
					    if the size, alignment, and bound‐
					    ary constraints would already sat‐
					    isfy the platform's requirements,
					    this flag is silently ignored.
					    The BUS_DMA_STREAMING flag will
					    never relax the constraints speci‐
					    fied in the call.
			 BUS_DMA_BUS[1-4]   These flags are placeholders, and
					    may be used by busses to provide
					    bus-dependent functionality.

	      All pages allocated by bus_dmamem_alloc() will be wired down
	      until they are freed by bus_dmamem_free().

	      Behavior is undefined if invalid arguments are passed to
	      bus_dmamem_alloc().

	      Returns 0 on success, or an error code indicating mode of fail‐
	      ure.

     bus_dmamem_free(tag, segs, nsegs)
	      Frees memory previously allocated by bus_dmamem_alloc().	Any
	      mappings will be invalidated.  Arguments are as follows:
	      tag    This is the bus_dma_tag_t passed down from the parent
		     driver via <bus>_attach_args.
	      segs   The array of bus_dma_segment_t's filled in by
		     bus_dmamem_alloc().
	      nsegs  The number of segments in segs.

	      Behavior is undefined if invalid arguments are passed to
	      bus_dmamem_free().

	      If given valid arguments, bus_dmamem_free() always succeeds.

     bus_dmamem_map(tag, segs, nsegs, size, kvap, flags)
	      Maps memory allocated with bus_dmamem_alloc() into kernel vir‐
	      tual address space.  Arguments are as follows:
	      tag    This is the bus_dma_tag_t passed down from the parent
		     driver via <bus>_attach_args.
	      segs   The array of bus_dma_segment_t's filled in by
		     bus_dmamem_alloc(), representing the memory regions to
		     map.
	      nsegs  The number of segments in segs.
	      size   The size of the mapping.
	      kvap   Filled in to specify the kernel virtual address where the
		     memory is mapped.
	      flags  Flags are defined as follows:
		     BUS_DMA_WAITOK    It is safe to wait (sleep) for
				       resources during this call.
		     BUS_DMA_NOWAIT    It is not safe to wait (sleep) for
				       resources during this call.
		     BUS_DMA_BUS[1-4]  These flags are placeholders, and may
				       be used by busses to provide bus-depen‐
				       dent functionality.
		     BUS_DMA_COHERENT  This flag is a hint to machine-depen‐
				       dent code.  If possible, map the memory
				       in such a way as it will be DMA coher‐
				       ent.  This may include mapping the
				       pages into uncached address space or
				       setting the cache-inhibit bits in page
				       table entries.  If DMA coherent map‐
				       pings are impossible, this flag is
				       silently ignored.

				       Later, when this memory is loaded into
				       a DMA map, machine-dependent code will
				       take whatever steps are necessary to
				       determine if the memory was mapped in a
				       DMA coherent fashion.  This may include
				       checking if the kernel virtual address
				       lies within uncached address space or
				       if the cache-inhibit bits are set in
				       page table entries.  If it is deter‐
				       mined that the mapping is DMA coherent,
				       state may be placed into the DMA map
				       for use by later calls to
				       bus_dmamap_sync().

				       Note that a device driver must not rely
				       on BUS_DMA_COHERENT for correct opera‐
				       tion.  All calls to bus_dmamap_sync()
				       must still be made.  This flag is pro‐
				       vided only as an optimization hint to
				       machine-dependent code.

				       Also note that this flag only applies
				       to coherency between the CPU and mem‐
				       ory.  Coherency between memory and the
				       device is controlled with a different
				       flag.  See the description of the
				       bus_dmamap_load() function.
		     BUS_DMA_NOCACHE   This flag is a hint to machine-depen‐
				       dent code.  If possible, map the
				       uncached memory.	 This flag may be use‐
				       ful in the case that the memory cache
				       causes unexpected behavior of the
				       device.

	      Behavior is undefined if invalid arguments are passed to
	      bus_dmamem_map().

	      Returns 0 on success, or an error code indicating mode of fail‐
	      ure.

     bus_dmamem_unmap(tag, kva, size)
	      Unmaps memory previously mapped with bus_dmamem_map(), freeing
	      the kernel virtual address space used by the mapping.  The argu‐
	      ments are as follows:
	      tag   This is the bus_dma_tag_t passed down from the parent
		    driver via <bus>_attach_args.
	      kva   The kernel virtual address of the mapped memory.
	      size  The size of the mapping.

	      Behavior is undefined if invalid arguments are passed to
	      bus_dmamem_unmap().

	      If given valid arguments, bus_dmamem_unmap() always succeeds.

     bus_dmamem_mmap(tag, segs, nsegs, off, prot, flags)
	      Provides support for user mmap(2)'ing of DMA-safe memory.	 This
	      function is to be called by a device driver's (*d_mmap)() entry
	      point, which is called by the device pager for each page to be
	      mapped.  The arguments are as follows:
	      tag    This is the bus_dma_tag_t passed down from the parent
		     driver via <bus>_attach_args.
	      segs   The array of bus_dma_segment_t's filled in by
		     bus_dmamem_alloc(), representing the memory to be
		     mmap(2)'ed.
	      nsegs  The number of elements in the segs array.
	      off    The offset of the page in DMA memory which is to be
		     mapped.
	      prot   The protection codes for the mapping.
	      flags  Flags are defined as follows:
		     BUS_DMA_WAITOK    It is safe to wait (sleep) for
				       resources during this call.
		     BUS_DMA_NOWAIT    It is not safe to wait (sleep) for
				       resources during this call.
		     BUS_DMA_BUS[1-4]  These flags are placeholders, and may
				       be used by busses to provide bus-depen‐
				       dent functionality.
		     BUS_DMA_COHERENT  See bus_dmamem_map() above for a
				       description of this flag.
		     BUS_DMA_NOCACHE   See bus_dmamem_map() above for a
				       description of this flag.

	      Behavior is undefined if invalid arguments are passed to
	      bus_dmamem_mmap().

	      Returns -1 to indicate failure.  Otherwise, returns an opaque
	      value to be interpreted by the device pager.

     bus_dmatag_subregion(tag, min_addr, max_addr, newtag, flags)
	      Given a bus_dma_tag_t create a new bus_dma_tag_t with a limited
	      bus address space.  This function should not normally be used,
	      but is useful for devices that do not support the full address
	      space of the parent bus.	The arguments are as follows:
	      tag	This is the bus_dma_tag_t to subregion.
	      min_addr	The smallest address this new tag can address.
	      max_addr.
			The largest address this new tag can address.
	      newtag	Pointer filled in with the address of the new
			bus_dma_tag_t.
	      flags	Flags are defined as follows:
			BUS_DMA_WAITOK	It is safe to wait (sleep) for
					resources during this call.
			BUS_DMA_NOWAIT	It is not safe to wait (sleep) for
					resources during this call.

     bus_dmatag_destroy(tag)
	      Free a tag created by bus_dmatag_subregion().

SEE ALSO
     bus_space(9), mb(9)

     Jason Thorpe, "A Machine-Independent DMA Framework for NetBSD",
     Proceedings of the FREENIX Track: 1998 USENIX Annual Technical
     Conference, USENIX Association,
     http://www.usenix.org/publications/library/proceedings/usenix98/freenix/thorpe_dma.pdf,
     1-12, June 15-19, 1998.

HISTORY
     The bus_dma interface appeared in NetBSD 1.3.

AUTHORS
     The bus_dma interface was designed and implemented by Jason R. Thorpe of
     the Numerical Aerospace Simulation Facility, NASA Ames Research Center.
     Additional input on the bus_dma design was provided by Chris Demetriou,
     Charles Hannum, Ross Harvey, Matthew Jacob, Jonathan Stone, and Matt
     Thomas.

BSD				 July 8, 2011				   BSD
[top]
                             _         _         _ 
                            | |       | |       | |     
                            | |       | |       | |     
                         __ | | __ __ | | __ __ | | __  
                         \ \| |/ / \ \| |/ / \ \| |/ /  
                          \ \ / /   \ \ / /   \ \ / /   
                           \   /     \   /     \   /    
                            \_/       \_/       \_/ 
More information is available in HTML format for server NetBSD

List of man pages available for NetBSD

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net