1If 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 12Raw pointer value SHOULD be printed with %p. The kernel supports 13the following extended format specifiers for pointer types: 14 15Symbols/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 38Kernel 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 46Struct 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 56Raw 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 66MAC/FDDI addresses: 67 68 %pM 00:01:02:03:04:05 69 %pMR 05:04:03:02:01:00 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 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 85IPv4 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 99IPv6 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 113UUID/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 128struct 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. 142 143u64 SHOULD be printed with %llu/%llx, (unsigned long long): 144 145 printk("%llu", (unsigned long long)u64_var); 146 147s64 SHOULD be printed with %lld/%llx, (long long): 148 149 printk("%lld", (long long)s64_var); 150 151If <type> is dependent on a config option for its size (e.g., sector_t, 152blkcnt_t, phys_addr_t, resource_size_t) or is architecture-dependent 153for its size (e.g., tcflag_t), use a format specifier of its largest 154possible 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 159Reminder: sizeof() result is of type size_t. 160 161Thank you for your cooperation and attention. 162 163 164By Randy Dunlap <rdunlap@xenotime.net> and 165Andrew Murray <amurray@mpc-data.co.uk> 166