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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 | ||
31550a16 AS |
56 | Raw buffer as a hex string: |
57 | %*ph 00 01 02 ... 3f | |
58 | %*phC 00:01:02: ... :3f | |
59 | %*phD 00-01-02- ... -3f | |
60 | %*phN 000102 ... 3f | |
61 | ||
62 | For printing a small buffers (up to 64 bytes long) as a hex string with | |
63 | certain separator. For the larger buffers consider to use | |
64 | print_hex_dump(). | |
65 | ||
04c55715 AM |
66 | MAC/FDDI addresses: |
67 | ||
68 | %pM 00:01:02:03:04:05 | |
76597ff9 | 69 | %pMR 05:04:03:02:01:00 |
04c55715 AM |
70 | %pMF 00-01-02-03-04-05 |
71 | %pm 000102030405 | |
72 | ||
73 | For printing 6-byte MAC/FDDI addresses in hex notation. The 'M' and 'm' | |
74 | specifiers result in a printed address with ('M') or without ('m') byte | |
75 | separators. The default byte separator is the colon (':'). | |
76 | ||
77 | Where FDDI addresses are concerned the 'F' specifier can be used after | |
78 | the 'M' specifier to use dash ('-') separators instead of the default | |
79 | separator. | |
80 | ||
76597ff9 AE |
81 | For Bluetooth addresses the 'R' specifier shall be used after the 'M' |
82 | specifier to use reversed byte order suitable for visual interpretation | |
83 | of Bluetooth addresses which are in the little endian order. | |
84 | ||
04c55715 AM |
85 | IPv4 addresses: |
86 | ||
87 | %pI4 1.2.3.4 | |
88 | %pi4 001.002.003.004 | |
89 | %p[Ii][hnbl] | |
90 | ||
91 | For printing IPv4 dot-separated decimal addresses. The 'I4' and 'i4' | |
92 | specifiers result in a printed address with ('i4') or without ('I4') | |
93 | leading zeros. | |
94 | ||
95 | The additional 'h', 'n', 'b', and 'l' specifiers are used to specify | |
96 | host, network, big or little endian order addresses respectively. Where | |
97 | no specifier is provided the default network/big endian order is used. | |
98 | ||
99 | IPv6 addresses: | |
100 | ||
101 | %pI6 0001:0002:0003:0004:0005:0006:0007:0008 | |
102 | %pi6 00010002000300040005000600070008 | |
103 | %pI6c 1:2:3:4:5:6:7:8 | |
104 | ||
105 | For printing IPv6 network-order 16-bit hex addresses. The 'I6' and 'i6' | |
106 | specifiers result in a printed address with ('I6') or without ('i6') | |
107 | colon-separators. Leading zeros are always used. | |
108 | ||
109 | The additional 'c' specifier can be used with the 'I' specifier to | |
110 | print a compressed IPv6 address as described by | |
111 | http://tools.ietf.org/html/rfc5952 | |
112 | ||
113 | UUID/GUID addresses: | |
114 | ||
115 | %pUb 00010203-0405-0607-0809-0a0b0c0d0e0f | |
116 | %pUB 00010203-0405-0607-0809-0A0B0C0D0E0F | |
117 | %pUl 03020100-0504-0706-0809-0a0b0c0e0e0f | |
118 | %pUL 03020100-0504-0706-0809-0A0B0C0E0E0F | |
119 | ||
120 | For printing 16-byte UUID/GUIDs addresses. The additional 'l', 'L', | |
121 | 'b' and 'B' specifiers are used to specify a little endian order in | |
122 | lower ('l') or upper case ('L') hex characters - and big endian order | |
123 | in lower ('b') or upper case ('B') hex characters. | |
124 | ||
125 | Where no additional specifiers are used the default little endian | |
126 | order with lower case hex characters will be printed. | |
127 | ||
128 | struct va_format: | |
129 | ||
130 | %pV | |
131 | ||
132 | For printing struct va_format structures. These contain a format string | |
133 | and va_list as follows: | |
134 | ||
135 | struct va_format { | |
136 | const char *fmt; | |
137 | va_list *va; | |
138 | }; | |
139 | ||
140 | Do not use this feature without some mechanism to verify the | |
141 | correctness of the format string and va_list arguments. | |
b67ad18b RD |
142 | |
143 | u64 SHOULD be printed with %llu/%llx, (unsigned long long): | |
144 | ||
145 | printk("%llu", (unsigned long long)u64_var); | |
146 | ||
147 | s64 SHOULD be printed with %lld/%llx, (long long): | |
148 | ||
149 | printk("%lld", (long long)s64_var); | |
150 | ||
151 | If <type> is dependent on a config option for its size (e.g., sector_t, | |
152 | blkcnt_t, phys_addr_t, resource_size_t) or is architecture-dependent | |
153 | for its size (e.g., tcflag_t), use a format specifier of its largest | |
154 | possible type and explicitly cast to it. Example: | |
155 | ||
156 | printk("test: sector number/total blocks: %llu/%llu\n", | |
157 | (unsigned long long)sector, (unsigned long long)blockcount); | |
158 | ||
159 | Reminder: sizeof() result is of type size_t. | |
160 | ||
161 | Thank you for your cooperation and attention. | |
162 | ||
163 | ||
04c55715 AM |
164 | By Randy Dunlap <rdunlap@xenotime.net> and |
165 | Andrew Murray <amurray@mpc-data.co.uk> |