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    The following form allows you to view linux man pages.

    Command:

    spufs

    
    
    
    

    DESCRIPTION

           The SPU file system is used on PowerPC machines that implement the Cell
           Broadband Engine Architecture in order to access Synergistic  Processor
           Units (SPUs).
    
           The file system provides a name space similar to posix shared memory or
           message queues. Users that have write permissions on  the  file  system
           can use spu_create(2) to establish SPU contexts in the spufs root.
    
           Every SPU context is represented by a directory containing a predefined
           set of files. These files can be used for manipulating the state of the
           logical SPU. Users can change permissions on those files, but not actu-
           ally add or remove files.
    
    
    

    MOUNT OPTIONS

           uid=<uid>
                  set the user owning the mount point, the default is 0 (root).
    
           gid=<gid>
                  set the group owning the mount point, the default is 0 (root).
    
    
    

    FILES

           The files in spufs mostly follow the standard behavior for regular sys-
           tem  calls like read(2) or write(2), but often support only a subset of
           the operations supported on regular file systems. This list details the
           supported  operations  and  the  deviations  from  the behaviour in the
           respective man pages.
    
           All files that support the read(2) operation also support readv(2)  and
           all  files  that support the write(2) operation also support writev(2).
           All files support the access(2) and stat(2) family of  operations,  but
           only  the  st_mode,  st_nlink,  st_uid and st_gid fields of struct stat
           contain reliable information.
    
           All files support the chmod(2)/fchmod(2) and chown(2)/fchown(2)  opera-
           tions,  but  will  not be able to grant permissions that contradict the
           possible operations, e.g. read access on the wbox file.
    
           The current set of files is:
    
       /mem
           the contents of the local storage memory  of  the  SPU.   This  can  be
           accessed  like  a regular shared memory file and contains both code and
           data in the address space of the SPU.  The possible  operations  on  an
           open mem file are:
    
           read(2), pread(2), write(2), pwrite(2), lseek(2)
                  These  operate  as  documented, with the exception that seek(2),
    
           operations on an open mbox file are:
    
           read(2)
                  If  a  count smaller than four is requested, read returns -1 and
                  sets errno to EINVAL.  If there is no data available in the mail
                  box,  the  return  value  is set to -1 and errno becomes EAGAIN.
                  When data has been read successfully, four bytes are  placed  in
                  the data buffer and the value four is returned.
    
       /ibox
           The  second  SPU  to CPU communication mailbox. This file is similar to
           the first mailbox file, but can be read in blocking I/O mode,  and  the
           poll  familiy of system calls can be used to wait for it.  The possible
           operations on an open ibox file are:
    
           read(2)
                  If a count smaller than four is requested, read returns  -1  and
                  sets errno to EINVAL.  If there is no data available in the mail
                  box and the file descriptor has been opened with O_NONBLOCK, the
                  return value is set to -1 and errno becomes EAGAIN.
    
                  If  there  is  no  data  available  in the mail box and the file
                  descriptor has been opened without  O_NONBLOCK,  the  call  will
                  block  until  the  SPU  writes to its interrupt mailbox channel.
                  When data has been read successfully, four bytes are  placed  in
                  the data buffer and the value four is returned.
    
           poll(2)
                  Poll  on  the  ibox  file returns (POLLIN | POLLRDNORM) whenever
                  data is available for reading.
    
       /wbox
           The CPU to SPU communation mailbox. It is write-only can can be written
           in  units  of  32  bits. If the mailbox is full, write() will block and
           poll can be used to wait for it becoming  empty  again.   The  possible
           operations  on  an open wbox file are: write(2) If a count smaller than
           four is requested, write returns -1 and sets errno to EINVAL.  If there
           is  no space available in the mail box and the file descriptor has been
           opened with O_NONBLOCK, the return value is set to -1 and errno becomes
           EAGAIN.
    
           If  there is no space available in the mail box and the file descriptor
           has been opened without O_NONBLOCK, the call will block until  the  SPU
           reads  from  its PPE mailbox channel.  When data has been read success-
           fully, four bytes are placed in the data buffer and the value  four  is
           returned.
    
           poll(2)
                  Poll  on  the  ibox file returns (POLLOUT | POLLWRNORM) whenever
                  space is available for writing.
                  the data buffer, containing the number of elements that  can  be
                  read  from  (for  mbox_stat  and  ibox_stat)  or written to (for
                  wbox_stat) the respective mail box without blocking or resulting
                  in EAGAIN.
    
       /npc
       /decr
       /decr_status
       /spu_tag_mask
       /event_mask
       /srr0
           Internal  registers  of  the SPU. The representation is an ASCII string
           with the numeric value of the next instruction to  be  executed.  These
           can  be  used in read/write mode for debugging, but normal operation of
           programs should not rely on them because access to any of  them  except
           npc requires an SPU context save and is therefore very inefficient.
    
           The contents of these files are:
    
           npc                 Next Program Counter
    
           decr                SPU Decrementer
    
           decr_status         Decrementer Status
    
           spu_tag_mask        MFC tag mask for SPU DMA
    
           event_mask          Event mask for SPU interrupts
    
           srr0                Interrupt Return address register
    
           The   possible   operations   on   an   open  npc,  decr,  decr_status,
           spu_tag_mask, event_mask or srr0 file are:
    
           read(2)
                  When the count supplied to the read call  is  shorter  than  the
                  required  length for the pointer value plus a newline character,
                  subsequent reads from the same file descriptor  will  result  in
                  completing  the string, regardless of changes to the register by
                  a running SPU task.  When a complete string has been  read,  all
                  subsequent read operations will return zero bytes and a new file
                  descriptor needs to be opened to read the value again.
    
           write(2)
                  A write operation on the file results in setting the register to
                  the  value  given  in  the string. The string is parsed from the
                  beginning to the first non-numeric character or the end  of  the
                  buffer.  Subsequent writes to the same file descriptor overwrite
                  the previous setting.
    
                  from the data buffer, updating the value of the fpcr register.
    
       /signal1
       /signal2
           The two signal notification channels of an SPU.  These  are  read-write
           files  that  operate  on  a 32 bit word.  Writing to one of these files
           triggers an interrupt on the SPU. The  value  writting  to  the  signal
           files can be read from the SPU through a channel read or from host user
           space through the file.  After the value has been read by the  SPU,  it
           is  reset  to zero.  The possible operations on an open signal1 or sig-
           nal2 file are:
    
           read(2)
                  If a count smaller than four is requested, read returns  -1  and
                  sets errno to EINVAL.  Otherwise, a four byte value is placed in
                  the data buffer, containing the current value of  the  specified
                  signal notification register.
    
           write(2)
                  If  a count smaller than four is requested, write returns -1 and
                  sets errno to EINVAL.  Otherwise, a four byte  value  is  copied
                  from the data buffer, updating the value of the specified signal
                  notification register.  The signal  notification  register  will
                  either be replaced with the input data or will be updated to the
                  bitwise OR or the old value and the input data, depending on the
                  contents  of  the  signal1_type,  or  signal2_type respectively,
                  file.
    
       /signal1_type
       /signal2_type
           These two files change the behavior of the signal1 and signal2  notifi-
           cation  files.  The  contain  a numerical ASCII string which is read as
           either "1" or "0".  In mode 0 (overwrite), the  hardware  replaces  the
           contents of the signal channel with the data that is written to it.  in
           mode 1 (logical OR), the hardware accumulates the bits that are  subse-
           quently written to it.  The possible operations on an open signal1_type
           or signal2_type file are:
    
           read(2)
                  When the count supplied to the read call  is  shorter  than  the
                  required  length  for the digit plus a newline character, subse-
                  quent reads from the same file descriptor will  result  in  com-
                  pleting  the  string.  When a complete string has been read, all
                  subsequent read operations will return zero bytes and a new file
                  descriptor needs to be opened to read the value again.
    
           write(2)
                  A write operation on the file results in setting the register to
                  the value given in the string. The string  is  parsed  from  the
                  beginning  to  the first non-numeric character or the end of the
    
           capabilities(7), close(2), spu_create(2), spu_run(2), spufs(7)
    
    
    

    Linux 2005-09-28 SPUFS(2)

    
    
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