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