diff options
Diffstat (limited to 'Documentation/printk-formats.txt')
-rw-r--r-- | Documentation/printk-formats.txt | 119 |
1 files changed, 117 insertions, 2 deletions
diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt index 1b5a5ddbc3e..5df176ed59b 100644 --- a/Documentation/printk-formats.txt +++ b/Documentation/printk-formats.txt | |||
@@ -9,7 +9,121 @@ If variable is of Type, use printk format specifier: | |||
9 | size_t %zu or %zx | 9 | size_t %zu or %zx |
10 | ssize_t %zd or %zx | 10 | ssize_t %zd or %zx |
11 | 11 | ||
12 | Raw pointer value SHOULD be printed with %p. | 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. | ||
13 | 127 | ||
14 | u64 SHOULD be printed with %llu/%llx, (unsigned long long): | 128 | u64 SHOULD be printed with %llu/%llx, (unsigned long long): |
15 | 129 | ||
@@ -32,4 +146,5 @@ Reminder: sizeof() result is of type size_t. | |||
32 | Thank you for your cooperation and attention. | 146 | Thank you for your cooperation and attention. |
33 | 147 | ||
34 | 148 | ||
35 | By Randy Dunlap <rdunlap@xenotime.net> | 149 | By Randy Dunlap <rdunlap@xenotime.net> and |
150 | Andrew Murray <amurray@mpc-data.co.uk> | ||