Commit | Line | Data |
---|---|---|
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 | ||
d7ec9a05 RV |
26 | The kernel's printf does not support %n. For obvious reasons, floating |
27 | point formats (%e, %f, %g, %a) are also not recognized. Use of any | |
28 | unsupported specifier or length qualifier results in a WARN and early | |
29 | return from vsnprintf. | |
b67ad18b | 30 | |
04c55715 AM |
31 | Raw pointer value SHOULD be printed with %p. The kernel supports |
32 | the following extended format specifiers for pointer types: | |
33 | ||
34 | Symbols/Function Pointers: | |
35 | ||
36 | %pF versatile_init+0x0/0x110 | |
37 | %pf versatile_init | |
38 | %pS versatile_init+0x0/0x110 | |
b0d33c2b JP |
39 | %pSR versatile_init+0x9/0x110 |
40 | (with __builtin_extract_return_addr() translation) | |
04c55715 AM |
41 | %ps versatile_init |
42 | %pB prev_fn_of_versatile_init+0x88/0x88 | |
43 | ||
44 | For printing symbols and function pointers. The 'S' and 's' specifiers | |
45 | result in the symbol name with ('S') or without ('s') offsets. Where | |
46 | this is used on a kernel without KALLSYMS - the symbol address is | |
47 | printed instead. | |
48 | ||
49 | The 'B' specifier results in the symbol name with offsets and should be | |
50 | used when printing stack backtraces. The specifier takes into | |
51 | consideration the effect of compiler optimisations which may occur | |
52 | when tail-call's are used and marked with the noreturn GCC attribute. | |
53 | ||
54 | On ia64, ppc64 and parisc64 architectures function pointers are | |
55 | actually function descriptors which must first be resolved. The 'F' and | |
56 | 'f' specifiers perform this resolution and then provide the same | |
57 | functionality as the 'S' and 's' specifiers. | |
58 | ||
59 | Kernel Pointers: | |
60 | ||
61 | %pK 0x01234567 or 0x0123456789abcdef | |
62 | ||
63 | For printing kernel pointers which should be hidden from unprivileged | |
64 | users. The behaviour of %pK depends on the kptr_restrict sysctl - see | |
65 | Documentation/sysctl/kernel.txt for more details. | |
66 | ||
67 | Struct Resources: | |
68 | ||
69 | %pr [mem 0x60000000-0x6fffffff flags 0x2200] or | |
70 | [mem 0x0000000060000000-0x000000006fffffff flags 0x2200] | |
71 | %pR [mem 0x60000000-0x6fffffff pref] or | |
72 | [mem 0x0000000060000000-0x000000006fffffff pref] | |
73 | ||
74 | For printing struct resources. The 'R' and 'r' specifiers result in a | |
75 | printed resource with ('R') or without ('r') a decoded flags member. | |
7330660e | 76 | Passed by reference. |
04c55715 | 77 | |
aaf07621 | 78 | Physical addresses types phys_addr_t: |
7d799210 | 79 | |
aaf07621 | 80 | %pa[p] 0x01234567 or 0x0123456789abcdef |
7d799210 SM |
81 | |
82 | For printing a phys_addr_t type (and its derivatives, such as | |
83 | resource_size_t) which can vary based on build options, regardless of | |
84 | the width of the CPU data path. Passed by reference. | |
85 | ||
aaf07621 JP |
86 | DMA addresses types dma_addr_t: |
87 | ||
88 | %pad 0x01234567 or 0x0123456789abcdef | |
89 | ||
90 | For printing a dma_addr_t type which can vary based on build options, | |
91 | regardless of the width of the CPU data path. Passed by reference. | |
92 | ||
71dca95d AS |
93 | Raw buffer as an escaped string: |
94 | ||
95 | %*pE[achnops] | |
96 | ||
97 | For printing raw buffer as an escaped string. For the following buffer | |
98 | ||
99 | 1b 62 20 5c 43 07 22 90 0d 5d | |
100 | ||
101 | few examples show how the conversion would be done (the result string | |
102 | without surrounding quotes): | |
103 | ||
104 | %*pE "\eb \C\a"\220\r]" | |
105 | %*pEhp "\x1bb \C\x07"\x90\x0d]" | |
106 | %*pEa "\e\142\040\\\103\a\042\220\r\135" | |
107 | ||
108 | The conversion rules are applied according to an optional combination | |
109 | of flags (see string_escape_mem() kernel documentation for the | |
110 | details): | |
111 | a - ESCAPE_ANY | |
112 | c - ESCAPE_SPECIAL | |
113 | h - ESCAPE_HEX | |
114 | n - ESCAPE_NULL | |
115 | o - ESCAPE_OCTAL | |
116 | p - ESCAPE_NP | |
117 | s - ESCAPE_SPACE | |
118 | By default ESCAPE_ANY_NP is used. | |
119 | ||
120 | ESCAPE_ANY_NP is the sane choice for many cases, in particularly for | |
121 | printing SSIDs. | |
122 | ||
123 | If field width is omitted the 1 byte only will be escaped. | |
124 | ||
31550a16 | 125 | Raw buffer as a hex string: |
5e4ee7b1 | 126 | |
31550a16 AS |
127 | %*ph 00 01 02 ... 3f |
128 | %*phC 00:01:02: ... :3f | |
129 | %*phD 00-01-02- ... -3f | |
130 | %*phN 000102 ... 3f | |
131 | ||
132 | For printing a small buffers (up to 64 bytes long) as a hex string with | |
133 | certain separator. For the larger buffers consider to use | |
134 | print_hex_dump(). | |
135 | ||
04c55715 AM |
136 | MAC/FDDI addresses: |
137 | ||
138 | %pM 00:01:02:03:04:05 | |
76597ff9 | 139 | %pMR 05:04:03:02:01:00 |
04c55715 AM |
140 | %pMF 00-01-02-03-04-05 |
141 | %pm 000102030405 | |
7c59154e | 142 | %pmR 050403020100 |
04c55715 AM |
143 | |
144 | For printing 6-byte MAC/FDDI addresses in hex notation. The 'M' and 'm' | |
145 | specifiers result in a printed address with ('M') or without ('m') byte | |
146 | separators. The default byte separator is the colon (':'). | |
147 | ||
148 | Where FDDI addresses are concerned the 'F' specifier can be used after | |
149 | the 'M' specifier to use dash ('-') separators instead of the default | |
150 | separator. | |
151 | ||
76597ff9 AE |
152 | For Bluetooth addresses the 'R' specifier shall be used after the 'M' |
153 | specifier to use reversed byte order suitable for visual interpretation | |
154 | of Bluetooth addresses which are in the little endian order. | |
155 | ||
7330660e GU |
156 | Passed by reference. |
157 | ||
04c55715 AM |
158 | IPv4 addresses: |
159 | ||
160 | %pI4 1.2.3.4 | |
161 | %pi4 001.002.003.004 | |
8ecada16 | 162 | %p[Ii]4[hnbl] |
04c55715 AM |
163 | |
164 | For printing IPv4 dot-separated decimal addresses. The 'I4' and 'i4' | |
165 | specifiers result in a printed address with ('i4') or without ('I4') | |
166 | leading zeros. | |
167 | ||
168 | The additional 'h', 'n', 'b', and 'l' specifiers are used to specify | |
169 | host, network, big or little endian order addresses respectively. Where | |
170 | no specifier is provided the default network/big endian order is used. | |
171 | ||
7330660e GU |
172 | Passed by reference. |
173 | ||
04c55715 AM |
174 | IPv6 addresses: |
175 | ||
176 | %pI6 0001:0002:0003:0004:0005:0006:0007:0008 | |
177 | %pi6 00010002000300040005000600070008 | |
178 | %pI6c 1:2:3:4:5:6:7:8 | |
179 | ||
180 | For printing IPv6 network-order 16-bit hex addresses. The 'I6' and 'i6' | |
181 | specifiers result in a printed address with ('I6') or without ('i6') | |
182 | colon-separators. Leading zeros are always used. | |
183 | ||
184 | The additional 'c' specifier can be used with the 'I' specifier to | |
185 | print a compressed IPv6 address as described by | |
186 | http://tools.ietf.org/html/rfc5952 | |
187 | ||
7330660e GU |
188 | Passed by reference. |
189 | ||
10679643 DB |
190 | IPv4/IPv6 addresses (generic, with port, flowinfo, scope): |
191 | ||
192 | %pIS 1.2.3.4 or 0001:0002:0003:0004:0005:0006:0007:0008 | |
193 | %piS 001.002.003.004 or 00010002000300040005000600070008 | |
194 | %pISc 1.2.3.4 or 1:2:3:4:5:6:7:8 | |
195 | %pISpc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345 | |
196 | %p[Ii]S[pfschnbl] | |
197 | ||
198 | For printing an IP address without the need to distinguish whether it's | |
199 | of type AF_INET or AF_INET6, a pointer to a valid 'struct sockaddr', | |
200 | specified through 'IS' or 'iS', can be passed to this format specifier. | |
201 | ||
202 | The additional 'p', 'f', and 's' specifiers are used to specify port | |
203 | (IPv4, IPv6), flowinfo (IPv6) and scope (IPv6). Ports have a ':' prefix, | |
204 | flowinfo a '/' and scope a '%', each followed by the actual value. | |
205 | ||
206 | In case of an IPv6 address the compressed IPv6 address as described by | |
207 | http://tools.ietf.org/html/rfc5952 is being used if the additional | |
208 | specifier 'c' is given. The IPv6 address is surrounded by '[', ']' in | |
209 | case of additional specifiers 'p', 'f' or 's' as suggested by | |
210 | https://tools.ietf.org/html/draft-ietf-6man-text-addr-representation-07 | |
211 | ||
212 | In case of IPv4 addresses, the additional 'h', 'n', 'b', and 'l' | |
213 | specifiers can be used as well and are ignored in case of an IPv6 | |
214 | address. | |
215 | ||
7330660e GU |
216 | Passed by reference. |
217 | ||
10679643 DB |
218 | Further examples: |
219 | ||
220 | %pISfc 1.2.3.4 or [1:2:3:4:5:6:7:8]/123456789 | |
221 | %pISsc 1.2.3.4 or [1:2:3:4:5:6:7:8]%1234567890 | |
222 | %pISpfc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345/123456789 | |
223 | ||
04c55715 AM |
224 | UUID/GUID addresses: |
225 | ||
226 | %pUb 00010203-0405-0607-0809-0a0b0c0d0e0f | |
227 | %pUB 00010203-0405-0607-0809-0A0B0C0D0E0F | |
228 | %pUl 03020100-0504-0706-0809-0a0b0c0e0e0f | |
229 | %pUL 03020100-0504-0706-0809-0A0B0C0E0E0F | |
230 | ||
231 | For printing 16-byte UUID/GUIDs addresses. The additional 'l', 'L', | |
232 | 'b' and 'B' specifiers are used to specify a little endian order in | |
233 | lower ('l') or upper case ('L') hex characters - and big endian order | |
234 | in lower ('b') or upper case ('B') hex characters. | |
235 | ||
d181b71c | 236 | Where no additional specifiers are used the default big endian |
04c55715 AM |
237 | order with lower case hex characters will be printed. |
238 | ||
7330660e GU |
239 | Passed by reference. |
240 | ||
4b6ccca7 | 241 | dentry names: |
5e4ee7b1 | 242 | |
4b6ccca7 AV |
243 | %pd{,2,3,4} |
244 | %pD{,2,3,4} | |
245 | ||
246 | For printing dentry name; if we race with d_move(), the name might be | |
247 | a mix of old and new ones, but it won't oops. %pd dentry is a safer | |
248 | equivalent of %s dentry->d_name.name we used to use, %pd<n> prints | |
249 | n last components. %pD does the same thing for struct file. | |
250 | ||
7330660e GU |
251 | Passed by reference. |
252 | ||
1031bc58 DM |
253 | block_device names: |
254 | ||
255 | %pg sda, sda1 or loop0p1 | |
256 | ||
257 | For printing name of block_device pointers. | |
258 | ||
04c55715 AM |
259 | struct va_format: |
260 | ||
261 | %pV | |
262 | ||
263 | For printing struct va_format structures. These contain a format string | |
264 | and va_list as follows: | |
265 | ||
266 | struct va_format { | |
267 | const char *fmt; | |
268 | va_list *va; | |
269 | }; | |
270 | ||
5e4ee7b1 MK |
271 | Implements a "recursive vsnprintf". |
272 | ||
04c55715 AM |
273 | Do not use this feature without some mechanism to verify the |
274 | correctness of the format string and va_list arguments. | |
b67ad18b | 275 | |
7330660e GU |
276 | Passed by reference. |
277 | ||
900cca29 GU |
278 | struct clk: |
279 | ||
280 | %pC pll1 | |
281 | %pCn pll1 | |
282 | %pCr 1560000000 | |
283 | ||
284 | For printing struct clk structures. '%pC' and '%pCn' print the name | |
285 | (Common Clock Framework) or address (legacy clock framework) of the | |
286 | structure; '%pCr' prints the current clock rate. | |
287 | ||
288 | Passed by reference. | |
289 | ||
d0724961 WL |
290 | bitmap and its derivatives such as cpumask and nodemask: |
291 | ||
292 | %*pb 0779 | |
293 | %*pbl 0,3-6,8-10 | |
294 | ||
295 | For printing bitmap and its derivatives such as cpumask and nodemask, | |
296 | %*pb output the bitmap with field width as the number of bits and %*pbl | |
297 | output the bitmap as range list with field width as the number of bits. | |
298 | ||
d6a24d06 | 299 | Passed by reference. |
b67ad18b | 300 | |
edf14cdb VB |
301 | Flags bitfields such as page flags, gfp_flags: |
302 | ||
303 | %pGp referenced|uptodate|lru|active|private | |
304 | %pGg GFP_USER|GFP_DMA32|GFP_NOWARN | |
305 | %pGv read|exec|mayread|maywrite|mayexec|denywrite | |
306 | ||
307 | For printing flags bitfields as a collection of symbolic constants that | |
308 | would construct the value. The type of flags is given by the third | |
309 | character. Currently supported are [p]age flags, [v]ma_flags (both | |
310 | expect unsigned long *) and [g]fp_flags (expects gfp_t *). The flag | |
311 | names and print order depends on the particular type. | |
312 | ||
313 | Note that this format should not be used directly in TP_printk() part | |
314 | of a tracepoint. Instead, use the show_*_flags() functions from | |
315 | <trace/events/mmflags.h>. | |
316 | ||
317 | Passed by reference. | |
318 | ||
5e4ee7b1 MK |
319 | Network device features: |
320 | ||
321 | %pNF 0x000000000000c000 | |
322 | ||
323 | For printing netdev_features_t. | |
324 | ||
325 | Passed by reference. | |
326 | ||
d7ec9a05 RV |
327 | If you add other %p extensions, please extend lib/test_printf.c with |
328 | one or more test cases, if at all feasible. | |
5e4ee7b1 | 329 | |
5e4ee7b1 | 330 | |
b67ad18b RD |
331 | Thank you for your cooperation and attention. |
332 | ||
333 | ||
755727b7 | 334 | By Randy Dunlap <rdunlap@infradead.org> and |
04c55715 | 335 | Andrew Murray <amurray@mpc-data.co.uk> |