Lines Matching +full:write +full:- +full:to +full:- +full:read
1 .. SPDX-License-Identifier: GPL-2.0
10 spufs - the SPU file system
17 Broadband Engine Architecture in order to access Synergistic Processor
20 The file system provides a name space similar to posix shared memory or
21 message queues. Users that have write permissions on the file system
22 can use spu_create(2) to establish SPU contexts in the spufs root.
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).
55 All files support the chmod(2)/fchmod(2) and chown(2)/fchown(2) opera-
56 tions, but will not be able to grant permissions that contradict the
57 possible operations, e.g. read access on the wbox file.
68 read(2), pread(2), write(2), pwrite(2), lseek(2)
70 write(2) and pwrite(2) are not supported beyond the end of the
75 Mapping mem into the process address space gives access to the
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
88 sets errno to EINVAL. If there is no data available in the mail
89 box, the return value is set to -1 and errno becomes EAGAIN.
90 When data has been read successfully, four bytes are placed in
95 The second SPU to CPU communication mailbox. This file is similar to
96 the first mailbox file, but can be read in blocking I/O mode, and the
97 poll family of system calls can be used to wait for it. The possible
100 read(2)
101 If a count smaller than four is requested, read returns -1 and
102 sets errno to EINVAL. If there is no data available in the mail
104 return value is set to -1 and errno becomes EAGAIN.
108 block until the SPU writes to its interrupt mailbox channel.
109 When data has been read successfully, four bytes are placed in
118 The CPU to SPU communation mailbox. It is write-only and can be written
119 in units of 32 bits. If the mailbox is full, write() will block and
120 poll can be used to wait for it becoming empty again. The possible
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-
139 Read-only files that contain the length of the current queue, i.e. how
140 many words can be read from mbox or ibox or how many words can be
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
149 read from (for mbox_stat and ibox_stat) or written to (for
156 with the numeric value of the next instruction to be executed. These
157 can be used in read/write mode for debugging, but normal operation of
158 programs should not rely on them because access to any of them except
176 read(2)
177 When the count supplied to the read call is shorter than the
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.
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
189 buffer. Subsequent writes to the same file descriptor overwrite
194 This file gives access to the Floating Point Status and Control Regis-
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
212 triggers an interrupt on the SPU. The value written to the signal
213 files can be read from the SPU through a channel read or from host user
214 space through the file. After the value has been read by the SPU, it
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
229 either be replaced with the input data or will be updated to the
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
239 contents of the signal channel with the data that is written to it. in
240 mode 1 (logical OR), the hardware accumulates the bits that are subse-
241 quently written to it. The possible operations on an open signal1_type
244 read(2)
245 When the count supplied to the read call is shorter than the
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
250 descriptor needs to be opened to read the value again.
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
256 buffer. Subsequent writes to the same file descriptor overwrite