1 .. SPDX-License-Identifier: GPL-2.0
2
3 =====
4 spufs
5 =====
6
7 Name
8 ====
9
10 spufs - the SPU file system
11
12
13 Description
14 ===========
15
16 The SPU file system is used on PowerPC
17 Broadband Engine Architecture in order
18 Units (SPUs).
19
20 The file system provides a name space s
21 message queues. Users that have write p
22 can use spu_create(2) to establish SPU
23
24 Every SPU context is represented by a d
25 set of files. These files can be used f
26 logical SPU. Users can change permissio
27 ally add or remove files.
28
29
30 Mount Options
31 =============
32
33 uid=<uid>
34 set the user owning the mount po
35
36 gid=<gid>
37 set the group owning the mount p
38
39
40 Files
41 =====
42
43 The files in spufs mostly follow the st
44 tem calls like read(2) or write(2), bu
45 the operations supported on regular fil
46 supported operations and the deviat
47 respective man pages.
48
49 All files that support the read(2) oper
50 all files that support the write(2) o
51 All files support the access(2) and sta
52 only the st_mode, st_nlink, st_uid
53 contain reliable information.
54
55 All files support the chmod(2)/fchmod(2
56 tions, but will not be able to grant
57 possible operations, e.g. read access o
58
59 The current set of files is:
60
61
62 /mem
63 the contents of the local storage memor
64 accessed like a regular shared memory
65 data in the address space of the SPU.
66 open mem file are:
67
68 read(2), pread(2), write(2), pwrite(2),
69 These operate as documented,
70 write(2) and pwrite(2) are not s
71 file. The file size is the size
72 which normally is 256 kilobytes.
73
74 mmap(2)
75 Mapping mem into the process add
76 SPU local storage within the
77 MAP_SHARED mappings are allowed.
78
79
80 /mbox
81 The first SPU to CPU communication mail
82 can be read in units of 32 bits. T
83 blocking mode and it even poll() will n
84 operations on an open mbox file are:
85
86 read(2)
87 If a count smaller than four i
88 sets errno to EINVAL. If there
89 box, the return value is set
90 When data has been read successf
91 the data buffer and the value fo
92
93
94 /ibox
95 The second SPU to CPU communication
96 the first mailbox file, but can be read
97 poll family of system calls can be use
98 operations on an open ibox file are:
99
100 read(2)
101 If a count smaller than four is
102 sets errno to EINVAL. If there
103 box and the file descriptor has
104 return value is set to -1 and er
105
106 If there is no data availab
107 descriptor has been opened witho
108 block until the SPU writes t
109 When data has been read successf
110 the data buffer and the value fo
111
112 poll(2)
113 Poll on the ibox file return
114 data is available for reading.
115
116
117 /wbox
118 The CPU to SPU communation mailbox. It
119 in units of 32 bits. If the mailbox
120 poll can be used to wait for it becomin
121 operations on an open wbox file are:
122 four is requested, write returns -1 and
123 is no space available in the mail box
124 opened with O_NONBLOCK, the return valu
125 EAGAIN.
126
127 If there is no space available in the
128 has been opened without O_NONBLOCK, the
129 reads from its PPE mailbox channel.
130 fully, four bytes are placed in the dat
131 returned.
132
133 poll(2)
134 Poll on the ibox file returns
135 space is available for writing.
136
137
138 /mbox_stat, /ibox_stat, /wbox_stat
139 Read-only files that contain the length
140 many words can be read from mbox
141 written to wbox without blocking. The
142 units and return a big-endian bina
143 operations on an open ``*box_stat`` fil
144
145 read(2)
146 If a count smaller than four is
147 sets errno to EINVAL. Otherwise
148 the data buffer, containing the
149 read from (for mbox_stat and
150 wbox_stat) the respective mail b
151 in EAGAIN.
152
153
154 /npc, /decr, /decr_status, /spu_tag_mask, /
155 Internal registers of the SPU. The r
156 with the numeric value of the next inst
157 can be used in read/write mode for de
158 programs should not rely on them becaus
159 npc requires an SPU context save and is
160
161 The contents of these files are:
162
163 =================== ===================
164 npc Next Program Counte
165 decr SPU Decrementer
166 decr_status Decrementer Status
167 spu_tag_mask MFC tag mask for SP
168 event_mask Event mask for SPU
169 srr0 Interrupt Return ad
170 =================== ===================
171
172
173 The possible operations on an
174 spu_tag_mask, event_mask or srr0 file a
175
176 read(2)
177 When the count supplied to the r
178 required length for the pointer
179 subsequent reads from the same f
180 completing the string, regardle
181 a running SPU task. When a comp
182 subsequent read operations will
183 descriptor needs to be opened to
184
185 write(2)
186 A write operation on the file re
187 the value given in the strin
188 beginning to the first non-numer
189 buffer. Subsequent writes to th
190 the previous setting.
191
192
193 /fpcr
194 This file gives access to the Floating
195 ter as a four byte long file. The opera
196
197 read(2)
198 If a count smaller than four i
199 sets errno to EINVAL. Otherwise
200 the data buffer, containing the
201 ter.
202
203 write(2)
204 If a count smaller than four is
205 sets errno to EINVAL. Otherw
206 from the data buffer, updating t
207
208
209 /signal1, /signal2
210 The two signal notification channels of
211 files that operate on a 32 bit word
212 triggers an interrupt on the SPU. The
213 files can be read from the SPU through
214 space through the file. After the valu
215 is reset to zero. The possible opera
216 nal2 file are:
217
218 read(2)
219 If a count smaller than four is
220 sets errno to EINVAL. Otherwise
221 the data buffer, containing the
222 signal notification register.
223
224 write(2)
225 If a count smaller than four is
226 sets errno to EINVAL. Otherwise
227 from the data buffer, updating t
228 notification register. The sign
229 either be replaced with the inpu
230 bitwise OR of the old value and
231 contents of the signal1_type,
232 file.
233
234
235 /signal1_type, /signal2_type
236 These two files change the behavior of
237 cation files. The contain a numeric
238 either "1" or "0". In mode 0 (overwrit
239 contents of the signal channel with the
240 mode 1 (logical OR), the hardware accum
241 quently written to it. The possible op
242 or signal2_type file are:
243
244 read(2)
245 When the count supplied to the r
246 required length for the digit
247 quent reads from the same file d
248 pleting the string. When a co
249 subsequent read operations will
250 descriptor needs to be opened to
251
252 write(2)
253 A write operation on the file re
254 the value given in the string. T
255 beginning to the first non-num
256 buffer. Subsequent writes to th
257 the previous setting.
258
259
260 Examples
261 ========
262 /etc/fstab entry
263 none /spu spufs gi
264
265
266 Authors
267 =======
268 Arnd Bergmann <arndb@de.ibm.com>, Mar
269 Ulrich Weigand <Ulrich.Weigand@de.ibm.co
270
271 See Also
272 ========
273 capabilities(7), close(2), spu_create(2
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