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Based on kernel version 3.13. Page generated on 2014-01-20 22:03 EST.

1	SPUFS(2)                   Linux Programmer's Manual                  SPUFS(2)
2	
3	
4	
5	NAME
6	       spufs - the SPU file system
7	
8	
9	DESCRIPTION
10	       The SPU file system is used on PowerPC machines that implement the Cell
11	       Broadband Engine Architecture in order to access Synergistic  Processor
12	       Units (SPUs).
13	
14	       The file system provides a name space similar to posix shared memory or
15	       message queues. Users that have write permissions on  the  file  system
16	       can use spu_create(2) to establish SPU contexts in the spufs root.
17	
18	       Every SPU context is represented by a directory containing a predefined
19	       set of files. These files can be used for manipulating the state of the
20	       logical SPU. Users can change permissions on those files, but not actu-
21	       ally add or remove files.
22	
23	
24	MOUNT OPTIONS
25	       uid=<uid>
26	              set the user owning the mount point, the default is 0 (root).
27	
28	       gid=<gid>
29	              set the group owning the mount point, the default is 0 (root).
30	
31	
32	FILES
33	       The files in spufs mostly follow the standard behavior for regular sys-
34	       tem  calls like read(2) or write(2), but often support only a subset of
35	       the operations supported on regular file systems. This list details the
36	       supported  operations  and  the  deviations  from  the behaviour in the
37	       respective man pages.
38	
39	       All files that support the read(2) operation also support readv(2)  and
40	       all  files  that support the write(2) operation also support writev(2).
41	       All files support the access(2) and stat(2) family of  operations,  but
42	       only  the  st_mode,  st_nlink,  st_uid and st_gid fields of struct stat
43	       contain reliable information.
44	
45	       All files support the chmod(2)/fchmod(2) and chown(2)/fchown(2)  opera-
46	       tions,  but  will  not be able to grant permissions that contradict the
47	       possible operations, e.g. read access on the wbox file.
48	
49	       The current set of files is:
50	
51	
52	   /mem
53	       the contents of the local storage memory  of  the  SPU.   This  can  be
54	       accessed  like  a regular shared memory file and contains both code and
55	       data in the address space of the SPU.  The possible  operations  on  an
56	       open mem file are:
57	
58	       read(2), pread(2), write(2), pwrite(2), lseek(2)
59	              These  operate  as  documented, with the exception that seek(2),
60	              write(2) and pwrite(2) are not supported beyond the end  of  the
61	              file. The file size is the size of the local storage of the SPU,
62	              which normally is 256 kilobytes.
63	
64	       mmap(2)
65	              Mapping mem into the process address space gives access  to  the
66	              SPU  local  storage  within  the  process  address  space.  Only
67	              MAP_SHARED mappings are allowed.
68	
69	
70	   /mbox
71	       The first SPU to CPU communication mailbox. This file is read-only  and
72	       can  be  read  in  units of 32 bits.  The file can only be used in non-
73	       blocking mode and it even poll() will not block on  it.   The  possible
74	       operations on an open mbox file are:
75	
76	       read(2)
77	              If  a  count smaller than four is requested, read returns -1 and
78	              sets errno to EINVAL.  If there is no data available in the mail
79	              box,  the  return  value  is set to -1 and errno becomes EAGAIN.
80	              When data has been read successfully, four bytes are  placed  in
81	              the data buffer and the value four is returned.
82	
83	
84	   /ibox
85	       The  second  SPU  to CPU communication mailbox. This file is similar to
86	       the first mailbox file, but can be read in blocking I/O mode,  and  the
87	       poll  family of system calls can be used to wait for it.  The  possible
88	       operations on an open ibox file are:
89	
90	       read(2)
91	              If a count smaller than four is requested, read returns  -1  and
92	              sets errno to EINVAL.  If there is no data available in the mail
93	              box and the file descriptor has been opened with O_NONBLOCK, the
94	              return value is set to -1 and errno becomes EAGAIN.
95	
96	              If  there  is  no  data  available  in the mail box and the file
97	              descriptor has been opened without  O_NONBLOCK,  the  call  will
98	              block  until  the  SPU  writes to its interrupt mailbox channel.
99	              When data has been read successfully, four bytes are  placed  in
100	              the data buffer and the value four is returned.
101	
102	       poll(2)
103	              Poll  on  the  ibox  file returns (POLLIN | POLLRDNORM) whenever
104	              data is available for reading.
105	
106	
107	   /wbox
108	       The CPU to SPU communation mailbox. It is write-only and can be written
109	       in  units  of  32  bits. If the mailbox is full, write() will block and
110	       poll can be used to wait for it becoming  empty  again.   The  possible
111	       operations  on  an open wbox file are: write(2) If a count smaller than
112	       four is requested, write returns -1 and sets errno to EINVAL.  If there
113	       is  no space available in the mail box and the file descriptor has been
114	       opened with O_NONBLOCK, the return value is set to -1 and errno becomes
115	       EAGAIN.
116	
117	       If  there is no space available in the mail box and the file descriptor
118	       has been opened without O_NONBLOCK, the call will block until  the  SPU
119	       reads  from  its PPE mailbox channel.  When data has been read success-
120	       fully, four bytes are placed in the data buffer and the value  four  is
121	       returned.
122	
123	       poll(2)
124	              Poll  on  the  ibox file returns (POLLOUT | POLLWRNORM) whenever
125	              space is available for writing.
126	
127	
128	   /mbox_stat
129	   /ibox_stat
130	   /wbox_stat
131	       Read-only files that contain the length of the current queue, i.e.  how
132	       many  words  can  be  read  from  mbox or ibox or how many words can be
133	       written to wbox without blocking.  The files can be read only in 4-byte
134	       units  and  return  a  big-endian  binary integer number.  The possible
135	       operations on an open *box_stat file are:
136	
137	       read(2)
138	              If a count smaller than four is requested, read returns  -1  and
139	              sets errno to EINVAL.  Otherwise, a four byte value is placed in
140	              the data buffer, containing the number of elements that  can  be
141	              read  from  (for  mbox_stat  and  ibox_stat)  or written to (for
142	              wbox_stat) the respective mail box without blocking or resulting
143	              in EAGAIN.
144	
145	
146	   /npc
147	   /decr
148	   /decr_status
149	   /spu_tag_mask
150	   /event_mask
151	   /srr0
152	       Internal  registers  of  the SPU. The representation is an ASCII string
153	       with the numeric value of the next instruction to  be  executed.  These
154	       can  be  used in read/write mode for debugging, but normal operation of
155	       programs should not rely on them because access to any of  them  except
156	       npc requires an SPU context save and is therefore very inefficient.
157	
158	       The contents of these files are:
159	
160	       npc                 Next Program Counter
161	
162	       decr                SPU Decrementer
163	
164	       decr_status         Decrementer Status
165	
166	       spu_tag_mask        MFC tag mask for SPU DMA
167	
168	       event_mask          Event mask for SPU interrupts
169	
170	       srr0                Interrupt Return address register
171	
172	
173	       The   possible   operations   on   an   open  npc,  decr,  decr_status,
174	       spu_tag_mask, event_mask or srr0 file are:
175	
176	       read(2)
177	              When the count supplied to the read call  is  shorter  than  the
178	              required  length for the pointer value plus a newline character,
179	              subsequent reads from the same file descriptor  will  result  in
180	              completing  the string, regardless of changes to the register by
181	              a running SPU task.  When a complete string has been  read,  all
182	              subsequent read operations will return zero bytes and a new file
183	              descriptor needs to be opened to read the value again.
184	
185	       write(2)
186	              A write operation on the file results in setting the register to
187	              the  value  given  in  the string. The string is parsed from the
188	              beginning to the first non-numeric character or the end  of  the
189	              buffer.  Subsequent writes to the same file descriptor overwrite
190	              the previous setting.
191	
192	
193	   /fpcr
194	       This file gives access to the Floating Point Status and Control  Regis-
195	       ter as a four byte long file. The operations on the fpcr file are:
196	
197	       read(2)
198	              If  a  count smaller than four is requested, read returns -1 and
199	              sets errno to EINVAL.  Otherwise, a four byte value is placed in
200	              the data buffer, containing the current value of the fpcr regis-
201	              ter.
202	
203	       write(2)
204	              If a count smaller than four is requested, write returns -1  and
205	              sets  errno  to  EINVAL.  Otherwise, a four byte value is copied
206	              from the data buffer, updating the value of the fpcr register.
207	
208	
209	   /signal1
210	   /signal2
211	       The two signal notification channels of an SPU.  These  are  read-write
212	       files  that  operate  on  a 32 bit word.  Writing to one of these files
213	       triggers an interrupt on the SPU.  The  value  written  to  the  signal
214	       files can be read from the SPU through a channel read or from host user
215	       space through the file.  After the value has been read by the  SPU,  it
216	       is  reset  to zero.  The possible operations on an open signal1 or sig-
217	       nal2 file are:
218	
219	       read(2)
220	              If a count smaller than four is requested, read returns  -1  and
221	              sets errno to EINVAL.  Otherwise, a four byte value is placed in
222	              the data buffer, containing the current value of  the  specified
223	              signal notification register.
224	
225	       write(2)
226	              If  a count smaller than four is requested, write returns -1 and
227	              sets errno to EINVAL.  Otherwise, a four byte  value  is  copied
228	              from the data buffer, updating the value of the specified signal
229	              notification register.  The signal  notification  register  will
230	              either be replaced with the input data or will be updated to the
231	              bitwise OR or the old value and the input data, depending on the
232	              contents  of  the  signal1_type,  or  signal2_type respectively,
233	              file.
234	
235	
236	   /signal1_type
237	   /signal2_type
238	       These two files change the behavior of the signal1 and signal2  notifi-
239	       cation  files.  The  contain  a numerical ASCII string which is read as
240	       either "1" or "0".  In mode 0 (overwrite), the  hardware  replaces  the
241	       contents of the signal channel with the data that is written to it.  in
242	       mode 1 (logical OR), the hardware accumulates the bits that are  subse-
243	       quently written to it.  The possible operations on an open signal1_type
244	       or signal2_type file are:
245	
246	       read(2)
247	              When the count supplied to the read call  is  shorter  than  the
248	              required  length  for the digit plus a newline character, subse-
249	              quent reads from the same file descriptor will  result  in  com-
250	              pleting  the  string.  When a complete string has been read, all
251	              subsequent read operations will return zero bytes and a new file
252	              descriptor needs to be opened to read the value again.
253	
254	       write(2)
255	              A write operation on the file results in setting the register to
256	              the value given in the string. The string  is  parsed  from  the
257	              beginning  to  the first non-numeric character or the end of the
258	              buffer.  Subsequent writes to the same file descriptor overwrite
259	              the previous setting.
260	
261	
262	EXAMPLES
263	       /etc/fstab entry
264	              none      /spu      spufs     gid=spu   0    0
265	
266	
267	AUTHORS
268	       Arnd  Bergmann  <arndb@de.ibm.com>,  Mark  Nutter <mnutter@us.ibm.com>,
269	       Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
270	
271	SEE ALSO
272	       capabilities(7), close(2), spu_create(2), spu_run(2), spufs(7)
273	
274	
275	
276	Linux                             2005-09-28                          SPUFS(2)
277	
278	------------------------------------------------------------------------------
279	
280	SPU_RUN(2)                 Linux Programmer's Manual                SPU_RUN(2)
281	
282	
283	
284	NAME
285	       spu_run - execute an spu context
286	
287	
288	SYNOPSIS
289	       #include <sys/spu.h>
290	
291	       int spu_run(int fd, unsigned int *npc, unsigned int *event);
292	
293	DESCRIPTION
294	       The  spu_run system call is used on PowerPC machines that implement the
295	       Cell Broadband Engine Architecture in order to access Synergistic  Pro-
296	       cessor  Units  (SPUs).  It  uses the fd that was returned from spu_cre-
297	       ate(2) to address a specific SPU context. When the context gets  sched-
298	       uled  to a physical SPU, it starts execution at the instruction pointer
299	       passed in npc.
300	
301	       Execution of SPU code happens synchronously, meaning that spu_run  does
302	       not  return  while the SPU is still running. If there is a need to exe-
303	       cute SPU code in parallel with other code on either  the  main  CPU  or
304	       other  SPUs,  you  need to create a new thread of execution first, e.g.
305	       using the pthread_create(3) call.
306	
307	       When spu_run returns, the current value of the SPU instruction  pointer
308	       is  written back to npc, so you can call spu_run again without updating
309	       the pointers.
310	
311	       event can be a NULL pointer or point to an extended  status  code  that
312	       gets  filled  when spu_run returns. It can be one of the following con-
313	       stants:
314	
315	       SPE_EVENT_DMA_ALIGNMENT
316	              A DMA alignment error
317	
318	       SPE_EVENT_SPE_DATA_SEGMENT
319	              A DMA segmentation error
320	
321	       SPE_EVENT_SPE_DATA_STORAGE
322	              A DMA storage error
323	
324	       If NULL is passed as the event argument, these errors will result in  a
325	       signal delivered to the calling process.
326	
327	RETURN VALUE
328	       spu_run  returns the value of the spu_status register or -1 to indicate
329	       an error and set errno to one of the error  codes  listed  below.   The
330	       spu_status  register  value  contains  a  bit  mask of status codes and
331	       optionally a 14 bit code returned from the stop-and-signal  instruction
332	       on the SPU. The bit masks for the status codes are:
333	
334	       0x02   SPU was stopped by stop-and-signal.
335	
336	       0x04   SPU was stopped by halt.
337	
338	       0x08   SPU is waiting for a channel.
339	
340	       0x10   SPU is in single-step mode.
341	
342	       0x20   SPU has tried to execute an invalid instruction.
343	
344	       0x40   SPU has tried to access an invalid channel.
345	
346	       0x3fff0000
347	              The  bits  masked with this value contain the code returned from
348	              stop-and-signal.
349	
350	       There are always one or more of the lower eight bits set  or  an  error
351	       code is returned from spu_run.
352	
353	ERRORS
354	       EAGAIN or EWOULDBLOCK
355	              fd is in non-blocking mode and spu_run would block.
356	
357	       EBADF  fd is not a valid file descriptor.
358	
359	       EFAULT npc is not a valid pointer or status is neither NULL nor a valid
360	              pointer.
361	
362	       EINTR  A signal occurred while spu_run was in progress.  The npc  value
363	              has  been updated to the new program counter value if necessary.
364	
365	       EINVAL fd is not a file descriptor returned from spu_create(2).
366	
367	       ENOMEM Insufficient memory was available to handle a page fault result-
368	              ing from an MFC direct memory access.
369	
370	       ENOSYS the functionality is not provided by the current system, because
371	              either the hardware does not provide SPUs or the spufs module is
372	              not loaded.
373	
374	
375	NOTES
376	       spu_run  is  meant  to  be  used  from  libraries that implement a more
377	       abstract interface to SPUs, not to be used from  regular  applications.
378	       See  http://www.bsc.es/projects/deepcomputing/linuxoncell/ for the rec-
379	       ommended libraries.
380	
381	
382	CONFORMING TO
383	       This call is Linux specific and only implemented by the ppc64 architec-
384	       ture. Programs using this system call are not portable.
385	
386	
387	BUGS
388	       The code does not yet fully implement all features lined out here.
389	
390	
391	AUTHOR
392	       Arnd Bergmann <arndb@de.ibm.com>
393	
394	SEE ALSO
395	       capabilities(7), close(2), spu_create(2), spufs(7)
396	
397	
398	
399	Linux                             2005-09-28                        SPU_RUN(2)
400	
401	------------------------------------------------------------------------------
402	
403	SPU_CREATE(2)              Linux Programmer's Manual             SPU_CREATE(2)
404	
405	
406	
407	NAME
408	       spu_create - create a new spu context
409	
410	
411	SYNOPSIS
412	       #include <sys/types.h>
413	       #include <sys/spu.h>
414	
415	       int spu_create(const char *pathname, int flags, mode_t mode);
416	
417	DESCRIPTION
418	       The  spu_create  system call is used on PowerPC machines that implement
419	       the Cell Broadband Engine Architecture in order to  access  Synergistic
420	       Processor  Units (SPUs). It creates a new logical context for an SPU in
421	       pathname and returns a handle to associated  with  it.   pathname  must
422	       point  to  a  non-existing directory in the mount point of the SPU file
423	       system (spufs).  When spu_create is successful, a directory  gets  cre-
424	       ated on pathname and it is populated with files.
425	
426	       The  returned  file  handle can only be passed to spu_run(2) or closed,
427	       other operations are not defined on it. When it is closed, all  associ-
428	       ated  directory entries in spufs are removed. When the last file handle
429	       pointing either inside  of  the  context  directory  or  to  this  file
430	       descriptor is closed, the logical SPU context is destroyed.
431	
432	       The  parameter flags can be zero or any bitwise or'd combination of the
433	       following constants:
434	
435	       SPU_RAWIO
436	              Allow mapping of some of the hardware registers of the SPU  into
437	              user space. This flag requires the CAP_SYS_RAWIO capability, see
438	              capabilities(7).
439	
440	       The mode parameter specifies the permissions used for creating the  new
441	       directory  in  spufs.   mode is modified with the user's umask(2) value
442	       and then used for both the directory and the files contained in it. The
443	       file permissions mask out some more bits of mode because they typically
444	       support only read or write access. See stat(2) for a full list  of  the
445	       possible mode values.
446	
447	
448	RETURN VALUE
449	       spu_create  returns a new file descriptor. It may return -1 to indicate
450	       an error condition and set errno to  one  of  the  error  codes  listed
451	       below.
452	
453	
454	ERRORS
455	       EACCESS
456	              The  current  user does not have write access on the spufs mount
457	              point.
458	
459	       EEXIST An SPU context already exists at the given path name.
460	
461	       EFAULT pathname is not a valid string pointer in  the  current  address
462	              space.
463	
464	       EINVAL pathname is not a directory in the spufs mount point.
465	
466	       ELOOP  Too many symlinks were found while resolving pathname.
467	
468	       EMFILE The process has reached its maximum open file limit.
469	
470	       ENAMETOOLONG
471	              pathname was too long.
472	
473	       ENFILE The system has reached the global open file limit.
474	
475	       ENOENT Part of pathname could not be resolved.
476	
477	       ENOMEM The kernel could not allocate all resources required.
478	
479	       ENOSPC There  are  not  enough  SPU resources available to create a new
480	              context or the user specific limit for the number  of  SPU  con-
481	              texts has been reached.
482	
483	       ENOSYS the functionality is not provided by the current system, because
484	              either the hardware does not provide SPUs or the spufs module is
485	              not loaded.
486	
487	       ENOTDIR
488	              A part of pathname is not a directory.
489	
490	
491	
492	NOTES
493	       spu_create  is  meant  to  be used from libraries that implement a more
494	       abstract interface to SPUs, not to be used from  regular  applications.
495	       See  http://www.bsc.es/projects/deepcomputing/linuxoncell/ for the rec-
496	       ommended libraries.
497	
498	
499	FILES
500	       pathname must point to a location beneath the mount point of spufs.  By
501	       convention, it gets mounted in /spu.
502	
503	
504	CONFORMING TO
505	       This call is Linux specific and only implemented by the ppc64 architec-
506	       ture. Programs using this system call are not portable.
507	
508	
509	BUGS
510	       The code does not yet fully implement all features lined out here.
511	
512	
513	AUTHOR
514	       Arnd Bergmann <arndb@de.ibm.com>
515	
516	SEE ALSO
517	       capabilities(7), close(2), spu_run(2), spufs(7)
518	
519	
520	
521	Linux                             2005-09-28                     SPU_CREATE(2)
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