filesystems/spufs/spufs.rst

1 .. SPDX-License-Identifier: GPL-2.0
10        spufs - the SPU file system
26        logical SPU. Users can change permissions on those files, but not actu-
43        The files in spufs mostly follow the standard behavior for regular sys-
44        tem  calls like read(2) or write(2), but often support only a subset of
52        only  the  st_mode,  st_nlink,  st_uid and st_gid fields of struct stat
55        All files support the chmod(2)/fchmod(2) and chown(2)/fchown(2)  opera-
76               SPU  local  storage  within  the  process  address  space.  Only
81        The first SPU to CPU communication mailbox. This file is read-only  and
82        can  be  read  in  units of 32 bits.  The file can only be used in non-
83        blocking mode and it even poll() will not block on  it.   The  possible
87               If  a  count smaller than four is requested, read returns -1 and
89               box,  the  return  value  is set to -1 and errno becomes EAGAIN.
97        poll  family of system calls can be used to wait for it.  The  possible
101               If a count smaller than four is requested, read returns  -1  and
104               return value is set to -1 and errno becomes EAGAIN.
112        poll(2)
113               Poll  on  the  ibox  file returns (POLLIN | POLLRDNORM) whenever
118        The CPU to SPU communation mailbox. It is write-only and can be written
120        poll can be used to wait for it becoming  empty  again.   The  possible
122        four is requested, write returns -1 and sets errno to EINVAL.  If there
124        opened with O_NONBLOCK, the return value is set to -1 and errno becomes
129        reads  from  its PPE mailbox channel.  When data has been read success-
133        poll(2)
134               Poll  on  the  ibox file returns (POLLOUT | POLLWRNORM) whenever
139        Read-only files that contain the length of the current queue, i.e.  how
141        written to wbox without blocking.  The files can be read only in 4-byte
142        units  and  return  a  big-endian  binary integer number.  The possible
146               If a count smaller than four is requested, read returns  -1  and
188               beginning to the first non-numeric character or the end  of  the
194        This file gives access to the Floating Point Status and Control  Regis-
198               If  a  count smaller than four is requested, read returns -1 and
200               the data buffer, containing the current value of the fpcr regis-
204               If a count smaller than four is requested, write returns -1  and
210        The two signal notification channels of an SPU.  These  are  read-write
215        is  reset  to zero.  The possible operations on an open signal1 or sig-
219               If a count smaller than four is requested, read returns  -1  and
225               If  a count smaller than four is requested, write returns -1 and
236        These two files change the behavior of the signal1 and signal2  notifi-
240        mode 1 (logical OR), the hardware accumulates the bits that are  subse-
246               required  length  for the digit plus a newline character, subse-
247               quent reads from the same file descriptor will  result  in  com-
255               beginning  to  the first non-numeric character or the end of the