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Commit | Line | Data |
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b67ad18b RD |
1 | If variable is of Type, use printk format specifier: |
2 | --------------------------------------------------------- | |
3 | int %d or %x | |
4 | unsigned int %u or %x | |
5 | long %ld or %lx | |
6 | unsigned long %lu or %lx | |
7 | long long %lld or %llx | |
8 | unsigned long long %llu or %llx | |
9 | size_t %zu or %zx | |
10 | ssize_t %zd or %zx | |
e8a7ba5f GU |
11 | s32 %d or %x |
12 | u32 %u or %x | |
13 | s64 %lld or %llx | |
14 | u64 %llu or %llx | |
15 | ||
16 | If <type> is dependent on a config option for its size (e.g., sector_t, | |
17 | blkcnt_t) or is architecture-dependent for its size (e.g., tcflag_t), use a | |
18 | format specifier of its largest possible type and explicitly cast to it. | |
19 | Example: | |
20 | ||
21 | printk("test: sector number/total blocks: %llu/%llu\n", | |
22 | (unsigned long long)sector, (unsigned long long)blockcount); | |
23 | ||
24 | Reminder: sizeof() result is of type size_t. | |
25 | ||
b67ad18b | 26 | |
04c55715 AM |
27 | Raw pointer value SHOULD be printed with %p. The kernel supports |
28 | the following extended format specifiers for pointer types: | |
29 | ||
30 | Symbols/Function Pointers: | |
31 | ||
32 | %pF versatile_init+0x0/0x110 | |
33 | %pf versatile_init | |
34 | %pS versatile_init+0x0/0x110 | |
b0d33c2b JP |
35 | %pSR versatile_init+0x9/0x110 |
36 | (with __builtin_extract_return_addr() translation) | |
04c55715 AM |
37 | %ps versatile_init |
38 | %pB prev_fn_of_versatile_init+0x88/0x88 | |
39 | ||
40 | For printing symbols and function pointers. The 'S' and 's' specifiers | |
41 | result in the symbol name with ('S') or without ('s') offsets. Where | |
42 | this is used on a kernel without KALLSYMS - the symbol address is | |
43 | printed instead. | |
44 | ||
45 | The 'B' specifier results in the symbol name with offsets and should be | |
46 | used when printing stack backtraces. The specifier takes into | |
47 | consideration the effect of compiler optimisations which may occur | |
48 | when tail-call's are used and marked with the noreturn GCC attribute. | |
49 | ||
50 | On ia64, ppc64 and parisc64 architectures function pointers are | |
51 | actually function descriptors which must first be resolved. The 'F' and | |
52 | 'f' specifiers perform this resolution and then provide the same | |
53 | functionality as the 'S' and 's' specifiers. | |
54 | ||
55 | Kernel Pointers: | |
56 | ||
57 | %pK 0x01234567 or 0x0123456789abcdef | |
58 | ||
59 | For printing kernel pointers which should be hidden from unprivileged | |
60 | users. The behaviour of %pK depends on the kptr_restrict sysctl - see | |
61 | Documentation/sysctl/kernel.txt for more details. | |
62 | ||
63 | Struct Resources: | |
64 | ||
65 | %pr [mem 0x60000000-0x6fffffff flags 0x2200] or | |
66 | [mem 0x0000000060000000-0x000000006fffffff flags 0x2200] | |
67 | %pR [mem 0x60000000-0x6fffffff pref] or | |
68 | [mem 0x0000000060000000-0x000000006fffffff pref] | |
69 | ||
70 | For printing struct resources. The 'R' and 'r' specifiers result in a | |
71 | printed resource with ('R') or without ('r') a decoded flags member. | |
7330660e | 72 | Passed by reference. |
04c55715 | 73 | |
aaf07621 | 74 | Physical addresses types phys_addr_t: |
7d799210 | 75 | |
aaf07621 | 76 | %pa[p] 0x01234567 or 0x0123456789abcdef |
7d799210 SM |
77 | |
78 | For printing a phys_addr_t type (and its derivatives, such as | |
79 | resource_size_t) which can vary based on build options, regardless of | |
80 | the width of the CPU data path. Passed by reference. | |
81 | ||
aaf07621 JP |
82 | DMA addresses types dma_addr_t: |
83 | ||
84 | %pad 0x01234567 or 0x0123456789abcdef | |
85 | ||
86 | For printing a dma_addr_t type which can vary based on build options, | |
87 | regardless of the width of the CPU data path. Passed by reference. | |
88 | ||
71dca95d AS |
89 | Raw buffer as an escaped string: |
90 | ||
91 | %*pE[achnops] | |
92 | ||
93 | For printing raw buffer as an escaped string. For the following buffer | |
94 | ||
95 | 1b 62 20 5c 43 07 22 90 0d 5d | |
96 | ||
97 | few examples show how the conversion would be done (the result string | |
98 | without surrounding quotes): | |
99 | ||
100 | %*pE "\eb \C\a"\220\r]" | |
101 | %*pEhp "\x1bb \C\x07"\x90\x0d]" | |
102 | %*pEa "\e\142\040\\\103\a\042\220\r\135" | |
103 | ||
104 | The conversion rules are applied according to an optional combination | |
105 | of flags (see string_escape_mem() kernel documentation for the | |
106 | details): | |
107 | a - ESCAPE_ANY | |
108 | c - ESCAPE_SPECIAL | |
109 | h - ESCAPE_HEX | |
110 | n - ESCAPE_NULL | |
111 | o - ESCAPE_OCTAL | |
112 | p - ESCAPE_NP | |
113 | s - ESCAPE_SPACE | |
114 | By default ESCAPE_ANY_NP is used. | |
115 | ||
116 | ESCAPE_ANY_NP is the sane choice for many cases, in particularly for | |
117 | printing SSIDs. | |
118 | ||
119 | If field width is omitted the 1 byte only will be escaped. | |
120 | ||
31550a16 | 121 | Raw buffer as a hex string: |
5e4ee7b1 | 122 | |
31550a16 AS |
123 | %*ph 00 01 02 ... 3f |
124 | %*phC 00:01:02: ... :3f | |
125 | %*phD 00-01-02- ... -3f | |
126 | %*phN 000102 ... 3f | |
127 | ||
128 | For printing a small buffers (up to 64 bytes long) as a hex string with | |
129 | certain separator. For the larger buffers consider to use | |
130 | print_hex_dump(). | |
131 | ||
04c55715 AM |
132 | MAC/FDDI addresses: |
133 | ||
134 | %pM 00:01:02:03:04:05 | |
76597ff9 | 135 | %pMR 05:04:03:02:01:00 |
04c55715 AM |
136 | %pMF 00-01-02-03-04-05 |
137 | %pm 000102030405 | |
7c59154e | 138 | %pmR 050403020100 |
04c55715 AM |
139 | |
140 | For printing 6-byte MAC/FDDI addresses in hex notation. The 'M' and 'm' | |
141 | specifiers result in a printed address with ('M') or without ('m') byte | |
142 | separators. The default byte separator is the colon (':'). | |
143 | ||
144 | Where FDDI addresses are concerned the 'F' specifier can be used after | |
145 | the 'M' specifier to use dash ('-') separators instead of the default | |
146 | separator. | |
147 | ||
76597ff9 AE |
148 | For Bluetooth addresses the 'R' specifier shall be used after the 'M' |
149 | specifier to use reversed byte order suitable for visual interpretation | |
150 | of Bluetooth addresses which are in the little endian order. | |
151 | ||
7330660e GU |
152 | Passed by reference. |
153 | ||
04c55715 AM |
154 | IPv4 addresses: |
155 | ||
156 | %pI4 1.2.3.4 | |
157 | %pi4 001.002.003.004 | |
8ecada16 | 158 | %p[Ii]4[hnbl] |
04c55715 AM |
159 | |
160 | For printing IPv4 dot-separated decimal addresses. The 'I4' and 'i4' | |
161 | specifiers result in a printed address with ('i4') or without ('I4') | |
162 | leading zeros. | |
163 | ||
164 | The additional 'h', 'n', 'b', and 'l' specifiers are used to specify | |
165 | host, network, big or little endian order addresses respectively. Where | |
166 | no specifier is provided the default network/big endian order is used. | |
167 | ||
7330660e GU |
168 | Passed by reference. |
169 | ||
04c55715 AM |
170 | IPv6 addresses: |
171 | ||
172 | %pI6 0001:0002:0003:0004:0005:0006:0007:0008 | |
173 | %pi6 00010002000300040005000600070008 | |
174 | %pI6c 1:2:3:4:5:6:7:8 | |
175 | ||
176 | For printing IPv6 network-order 16-bit hex addresses. The 'I6' and 'i6' | |
177 | specifiers result in a printed address with ('I6') or without ('i6') | |
178 | colon-separators. Leading zeros are always used. | |
179 | ||
180 | The additional 'c' specifier can be used with the 'I' specifier to | |
181 | print a compressed IPv6 address as described by | |
182 | http://tools.ietf.org/html/rfc5952 | |
183 | ||
7330660e GU |
184 | Passed by reference. |
185 | ||
10679643 DB |
186 | IPv4/IPv6 addresses (generic, with port, flowinfo, scope): |
187 | ||
188 | %pIS 1.2.3.4 or 0001:0002:0003:0004:0005:0006:0007:0008 | |
189 | %piS 001.002.003.004 or 00010002000300040005000600070008 | |
190 | %pISc 1.2.3.4 or 1:2:3:4:5:6:7:8 | |
191 | %pISpc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345 | |
192 | %p[Ii]S[pfschnbl] | |
193 | ||
194 | For printing an IP address without the need to distinguish whether it's | |
195 | of type AF_INET or AF_INET6, a pointer to a valid 'struct sockaddr', | |
196 | specified through 'IS' or 'iS', can be passed to this format specifier. | |
197 | ||
198 | The additional 'p', 'f', and 's' specifiers are used to specify port | |
199 | (IPv4, IPv6), flowinfo (IPv6) and scope (IPv6). Ports have a ':' prefix, | |
200 | flowinfo a '/' and scope a '%', each followed by the actual value. | |
201 | ||
202 | In case of an IPv6 address the compressed IPv6 address as described by | |
203 | http://tools.ietf.org/html/rfc5952 is being used if the additional | |
204 | specifier 'c' is given. The IPv6 address is surrounded by '[', ']' in | |
205 | case of additional specifiers 'p', 'f' or 's' as suggested by | |
206 | https://tools.ietf.org/html/draft-ietf-6man-text-addr-representation-07 | |
207 | ||
208 | In case of IPv4 addresses, the additional 'h', 'n', 'b', and 'l' | |
209 | specifiers can be used as well and are ignored in case of an IPv6 | |
210 | address. | |
211 | ||
7330660e GU |
212 | Passed by reference. |
213 | ||
10679643 DB |
214 | Further examples: |
215 | ||
216 | %pISfc 1.2.3.4 or [1:2:3:4:5:6:7:8]/123456789 | |
217 | %pISsc 1.2.3.4 or [1:2:3:4:5:6:7:8]%1234567890 | |
218 | %pISpfc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345/123456789 | |
219 | ||
04c55715 AM |
220 | UUID/GUID addresses: |
221 | ||
222 | %pUb 00010203-0405-0607-0809-0a0b0c0d0e0f | |
223 | %pUB 00010203-0405-0607-0809-0A0B0C0D0E0F | |
224 | %pUl 03020100-0504-0706-0809-0a0b0c0e0e0f | |
225 | %pUL 03020100-0504-0706-0809-0A0B0C0E0E0F | |
226 | ||
227 | For printing 16-byte UUID/GUIDs addresses. The additional 'l', 'L', | |
228 | 'b' and 'B' specifiers are used to specify a little endian order in | |
229 | lower ('l') or upper case ('L') hex characters - and big endian order | |
230 | in lower ('b') or upper case ('B') hex characters. | |
231 | ||
d181b71c | 232 | Where no additional specifiers are used the default big endian |
04c55715 AM |
233 | order with lower case hex characters will be printed. |
234 | ||
7330660e GU |
235 | Passed by reference. |
236 | ||
4b6ccca7 | 237 | dentry names: |
5e4ee7b1 | 238 | |
4b6ccca7 AV |
239 | %pd{,2,3,4} |
240 | %pD{,2,3,4} | |
241 | ||
242 | For printing dentry name; if we race with d_move(), the name might be | |
243 | a mix of old and new ones, but it won't oops. %pd dentry is a safer | |
244 | equivalent of %s dentry->d_name.name we used to use, %pd<n> prints | |
245 | n last components. %pD does the same thing for struct file. | |
246 | ||
7330660e GU |
247 | Passed by reference. |
248 | ||
04c55715 AM |
249 | struct va_format: |
250 | ||
251 | %pV | |
252 | ||
253 | For printing struct va_format structures. These contain a format string | |
254 | and va_list as follows: | |
255 | ||
256 | struct va_format { | |
257 | const char *fmt; | |
258 | va_list *va; | |
259 | }; | |
260 | ||
5e4ee7b1 MK |
261 | Implements a "recursive vsnprintf". |
262 | ||
04c55715 AM |
263 | Do not use this feature without some mechanism to verify the |
264 | correctness of the format string and va_list arguments. | |
b67ad18b | 265 | |
7330660e GU |
266 | Passed by reference. |
267 | ||
900cca29 GU |
268 | struct clk: |
269 | ||
270 | %pC pll1 | |
271 | %pCn pll1 | |
272 | %pCr 1560000000 | |
273 | ||
274 | For printing struct clk structures. '%pC' and '%pCn' print the name | |
275 | (Common Clock Framework) or address (legacy clock framework) of the | |
276 | structure; '%pCr' prints the current clock rate. | |
277 | ||
278 | Passed by reference. | |
279 | ||
d0724961 WL |
280 | bitmap and its derivatives such as cpumask and nodemask: |
281 | ||
282 | %*pb 0779 | |
283 | %*pbl 0,3-6,8-10 | |
284 | ||
285 | For printing bitmap and its derivatives such as cpumask and nodemask, | |
286 | %*pb output the bitmap with field width as the number of bits and %*pbl | |
287 | output the bitmap as range list with field width as the number of bits. | |
288 | ||
d6a24d06 | 289 | Passed by reference. |
b67ad18b | 290 | |
5e4ee7b1 MK |
291 | Network device features: |
292 | ||
293 | %pNF 0x000000000000c000 | |
294 | ||
295 | For printing netdev_features_t. | |
296 | ||
297 | Passed by reference. | |
298 | ||
299 | Command from struct task_struct | |
300 | ||
301 | %pT ls | |
302 | ||
303 | For printing executable name excluding path from struct | |
304 | task_struct. | |
305 | ||
306 | Passed by reference. | |
307 | ||
308 | Ignored argument: | |
309 | ||
310 | %n %n | |
311 | ||
312 | The argument passed will be ignored. In other words, literal "%n" will | |
313 | be in the output and the argument will be considered for next format | |
314 | specifier. | |
315 | ||
b67ad18b RD |
316 | Thank you for your cooperation and attention. |
317 | ||
318 | ||
755727b7 | 319 | By Randy Dunlap <rdunlap@infradead.org> and |
04c55715 | 320 | Andrew Murray <amurray@mpc-data.co.uk> |