1SPUFS(2)                   Linux Programmer's Manual                  SPUFS(2)
2
3
4
5NAME
6       spufs - the SPU file system
7
8
9DESCRIPTION
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
24MOUNT 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
32FILES
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
262EXAMPLES
263       /etc/fstab entry
264              none      /spu      spufs     gid=spu   0    0
265
266
267AUTHORS
268       Arnd  Bergmann  <arndb@de.ibm.com>,  Mark  Nutter <mnutter@us.ibm.com>,
269       Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
270
271SEE ALSO
272       capabilities(7), close(2), spu_create(2), spu_run(2), spufs(7)
273
274
275
276Linux                             2005-09-28                          SPUFS(2)
277
278------------------------------------------------------------------------------
279
280SPU_RUN(2)                 Linux Programmer's Manual                SPU_RUN(2)
281
282
283
284NAME
285       spu_run - execute an spu context
286
287
288SYNOPSIS
289       #include <sys/spu.h>
290
291       int spu_run(int fd, unsigned int *npc, unsigned int *event);
292
293DESCRIPTION
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
327RETURN 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
353ERRORS
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
375NOTES
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
382CONFORMING 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
387BUGS
388       The code does not yet fully implement all features lined out here.
389
390
391AUTHOR
392       Arnd Bergmann <arndb@de.ibm.com>
393
394SEE ALSO
395       capabilities(7), close(2), spu_create(2), spufs(7)
396
397
398
399Linux                             2005-09-28                        SPU_RUN(2)
400
401------------------------------------------------------------------------------
402
403SPU_CREATE(2)              Linux Programmer's Manual             SPU_CREATE(2)
404
405
406
407NAME
408       spu_create - create a new spu context
409
410
411SYNOPSIS
412       #include <sys/types.h>
413       #include <sys/spu.h>
414
415       int spu_create(const char *pathname, int flags, mode_t mode);
416
417DESCRIPTION
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
448RETURN 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
454ERRORS
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
492NOTES
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
499FILES
500       pathname must point to a location beneath the mount point of spufs.  By
501       convention, it gets mounted in /spu.
502
503
504CONFORMING 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
509BUGS
510       The code does not yet fully implement all features lined out here.
511
512
513AUTHOR
514       Arnd Bergmann <arndb@de.ibm.com>
515
516SEE ALSO
517       capabilities(7), close(2), spu_run(2), spufs(7)
518
519
520
521Linux                             2005-09-28                     SPU_CREATE(2)
522