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 | |
11 | ||
04c55715 AM |
12 | Raw pointer value SHOULD be printed with %p. The kernel supports |
13 | the following extended format specifiers for pointer types: | |
14 | ||
15 | Symbols/Function Pointers: | |
16 | ||
17 | %pF versatile_init+0x0/0x110 | |
18 | %pf versatile_init | |
19 | %pS versatile_init+0x0/0x110 | |
20 | %ps versatile_init | |
21 | %pB prev_fn_of_versatile_init+0x88/0x88 | |
22 | ||
23 | For printing symbols and function pointers. The 'S' and 's' specifiers | |
24 | result in the symbol name with ('S') or without ('s') offsets. Where | |
25 | this is used on a kernel without KALLSYMS - the symbol address is | |
26 | printed instead. | |
27 | ||
28 | The 'B' specifier results in the symbol name with offsets and should be | |
29 | used when printing stack backtraces. The specifier takes into | |
30 | consideration the effect of compiler optimisations which may occur | |
31 | when tail-call's are used and marked with the noreturn GCC attribute. | |
32 | ||
33 | On ia64, ppc64 and parisc64 architectures function pointers are | |
34 | actually function descriptors which must first be resolved. The 'F' and | |
35 | 'f' specifiers perform this resolution and then provide the same | |
36 | functionality as the 'S' and 's' specifiers. | |
37 | ||
38 | Kernel Pointers: | |
39 | ||
40 | %pK 0x01234567 or 0x0123456789abcdef | |
41 | ||
42 | For printing kernel pointers which should be hidden from unprivileged | |
43 | users. The behaviour of %pK depends on the kptr_restrict sysctl - see | |
44 | Documentation/sysctl/kernel.txt for more details. | |
45 | ||
46 | Struct Resources: | |
47 | ||
48 | %pr [mem 0x60000000-0x6fffffff flags 0x2200] or | |
49 | [mem 0x0000000060000000-0x000000006fffffff flags 0x2200] | |
50 | %pR [mem 0x60000000-0x6fffffff pref] or | |
51 | [mem 0x0000000060000000-0x000000006fffffff pref] | |
52 | ||
53 | For printing struct resources. The 'R' and 'r' specifiers result in a | |
54 | printed resource with ('R') or without ('r') a decoded flags member. | |
55 | ||
7d799210 SM |
56 | Physical addresses: |
57 | ||
58 | %pa 0x01234567 or 0x0123456789abcdef | |
59 | ||
60 | For printing a phys_addr_t type (and its derivatives, such as | |
61 | resource_size_t) which can vary based on build options, regardless of | |
62 | the width of the CPU data path. Passed by reference. | |
63 | ||
31550a16 AS |
64 | Raw buffer as a hex string: |
65 | %*ph 00 01 02 ... 3f | |
66 | %*phC 00:01:02: ... :3f | |
67 | %*phD 00-01-02- ... -3f | |
68 | %*phN 000102 ... 3f | |
69 | ||
70 | For printing a small buffers (up to 64 bytes long) as a hex string with | |
71 | certain separator. For the larger buffers consider to use | |
72 | print_hex_dump(). | |
73 | ||
04c55715 AM |
74 | MAC/FDDI addresses: |
75 | ||
76 | %pM 00:01:02:03:04:05 | |
76597ff9 | 77 | %pMR 05:04:03:02:01:00 |
04c55715 AM |
78 | %pMF 00-01-02-03-04-05 |
79 | %pm 000102030405 | |
7c59154e | 80 | %pmR 050403020100 |
04c55715 AM |
81 | |
82 | For printing 6-byte MAC/FDDI addresses in hex notation. The 'M' and 'm' | |
83 | specifiers result in a printed address with ('M') or without ('m') byte | |
84 | separators. The default byte separator is the colon (':'). | |
85 | ||
86 | Where FDDI addresses are concerned the 'F' specifier can be used after | |
87 | the 'M' specifier to use dash ('-') separators instead of the default | |
88 | separator. | |
89 | ||
76597ff9 AE |
90 | For Bluetooth addresses the 'R' specifier shall be used after the 'M' |
91 | specifier to use reversed byte order suitable for visual interpretation | |
92 | of Bluetooth addresses which are in the little endian order. | |
93 | ||
04c55715 AM |
94 | IPv4 addresses: |
95 | ||
96 | %pI4 1.2.3.4 | |
97 | %pi4 001.002.003.004 | |
98 | %p[Ii][hnbl] | |
99 | ||
100 | For printing IPv4 dot-separated decimal addresses. The 'I4' and 'i4' | |
101 | specifiers result in a printed address with ('i4') or without ('I4') | |
102 | leading zeros. | |
103 | ||
104 | The additional 'h', 'n', 'b', and 'l' specifiers are used to specify | |
105 | host, network, big or little endian order addresses respectively. Where | |
106 | no specifier is provided the default network/big endian order is used. | |
107 | ||
108 | IPv6 addresses: | |
109 | ||
110 | %pI6 0001:0002:0003:0004:0005:0006:0007:0008 | |
111 | %pi6 00010002000300040005000600070008 | |
112 | %pI6c 1:2:3:4:5:6:7:8 | |
113 | ||
114 | For printing IPv6 network-order 16-bit hex addresses. The 'I6' and 'i6' | |
115 | specifiers result in a printed address with ('I6') or without ('i6') | |
116 | colon-separators. Leading zeros are always used. | |
117 | ||
118 | The additional 'c' specifier can be used with the 'I' specifier to | |
119 | print a compressed IPv6 address as described by | |
120 | http://tools.ietf.org/html/rfc5952 | |
121 | ||
122 | UUID/GUID addresses: | |
123 | ||
124 | %pUb 00010203-0405-0607-0809-0a0b0c0d0e0f | |
125 | %pUB 00010203-0405-0607-0809-0A0B0C0D0E0F | |
126 | %pUl 03020100-0504-0706-0809-0a0b0c0e0e0f | |
127 | %pUL 03020100-0504-0706-0809-0A0B0C0E0E0F | |
128 | ||
129 | For printing 16-byte UUID/GUIDs addresses. The additional 'l', 'L', | |
130 | 'b' and 'B' specifiers are used to specify a little endian order in | |
131 | lower ('l') or upper case ('L') hex characters - and big endian order | |
132 | in lower ('b') or upper case ('B') hex characters. | |
133 | ||
134 | Where no additional specifiers are used the default little endian | |
135 | order with lower case hex characters will be printed. | |
136 | ||
137 | struct va_format: | |
138 | ||
139 | %pV | |
140 | ||
141 | For printing struct va_format structures. These contain a format string | |
142 | and va_list as follows: | |
143 | ||
144 | struct va_format { | |
145 | const char *fmt; | |
146 | va_list *va; | |
147 | }; | |
148 | ||
149 | Do not use this feature without some mechanism to verify the | |
150 | correctness of the format string and va_list arguments. | |
b67ad18b RD |
151 | |
152 | u64 SHOULD be printed with %llu/%llx, (unsigned long long): | |
153 | ||
154 | printk("%llu", (unsigned long long)u64_var); | |
155 | ||
156 | s64 SHOULD be printed with %lld/%llx, (long long): | |
157 | ||
158 | printk("%lld", (long long)s64_var); | |
159 | ||
160 | If <type> is dependent on a config option for its size (e.g., sector_t, | |
7d799210 SM |
161 | blkcnt_t) or is architecture-dependent for its size (e.g., tcflag_t), use a |
162 | format specifier of its largest possible type and explicitly cast to it. | |
163 | Example: | |
b67ad18b RD |
164 | |
165 | printk("test: sector number/total blocks: %llu/%llu\n", | |
166 | (unsigned long long)sector, (unsigned long long)blockcount); | |
167 | ||
168 | Reminder: sizeof() result is of type size_t. | |
169 | ||
170 | Thank you for your cooperation and attention. | |
171 | ||
172 | ||
755727b7 | 173 | By Randy Dunlap <rdunlap@infradead.org> and |
04c55715 | 174 | Andrew Murray <amurray@mpc-data.co.uk> |