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1 .. SPDX-License-Identifier: GPL-2.0
10 spufs - the SPU file system
20 The file system provides a name space similar to posix shared memory or
22 can use spu_create(2) to establish SPU contexts in the spufs root.
24 Every SPU context is represented by a directory containing a predefined
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
49 All files that support the read(2) operation also support readv(2) and
50 all files that support the write(2) operation also support writev(2).
51 All files support the access(2) and stat(2) family of operations, but
55 All files support the chmod(2)/fchmod(2) and chown(2)/fchown(2) opera-
64 accessed like a regular shared memory file and contains both code and
68 read(2), pread(2), write(2), pwrite(2), lseek(2)
69 These operate as documented, with the exception that seek(2),
70 write(2) and pwrite(2) are not supported beyond the end of the
74 mmap(2)
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-
86 read(2)
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.
100 read(2)
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)
118 The CPU to SPU communation mailbox. It is write-only and can be written
121 operations on an open wbox file are: write(2) If a count smaller than
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)
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
145 read(2)
146 If a count smaller than four is requested, read returns -1 and
147 sets errno to EINVAL. Otherwise, a four byte value is placed in
176 read(2)
178 required length for the pointer value plus a newline character,
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
185 write(2)
186 A write operation on the file results in setting the register to
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-
195 ter as a four byte long file. The operations on the fpcr file are:
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-
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
210 The two signal notification channels of an SPU. These are read-write
211 files that operate on a 32 bit word. Writing to one of these files
213 files can be read from the SPU through a channel read or from host user
215 is reset to zero. The possible operations on an open signal1 or sig-
218 read(2)
219 If a count smaller than four is requested, read returns -1 and
220 sets errno to EINVAL. Otherwise, a four byte value is placed in
224 write(2)
225 If a count smaller than four is requested, write returns -1 and
226 sets errno to EINVAL. Otherwise, a four byte value is copied
236 These two files change the behavior of the signal1 and signal2 notifi-
237 cation files. The contain a numerical ASCII string which is read as
240 mode 1 (logical OR), the hardware accumulates the bits that are subse-
244 read(2)
246 required length for the digit plus a newline character, subse-
247 quent reads from the same file descriptor will result in com-
248 pleting the string. When a complete string has been read, all
249 subsequent read operations will return zero bytes and a new file
252 write(2)
253 A write operation on the file results in setting the register to
255 beginning to the first non-numeric character or the end of the
273 capabilities(7), close(2), spu_create(2), spu_run(2), spufs(7)