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 56MAC/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 70IPv4 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 84IPv6 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 98UUID/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 113struct 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 128u64 SHOULD be printed with %llu/%llx, (unsigned long long): 129 130 printk("%llu", (unsigned long long)u64_var); 131 132s64 SHOULD be printed with %lld/%llx, (long long): 133 134 printk("%lld", (long long)s64_var); 135 136If <type> is dependent on a config option for its size (e.g., sector_t, 137blkcnt_t, phys_addr_t, resource_size_t) or is architecture-dependent 138for its size (e.g., tcflag_t), use a format specifier of its largest 139possible 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 144Reminder: sizeof() result is of type size_t. 145 146Thank you for your cooperation and attention. 147 148 149By Randy Dunlap <rdunlap@xenotime.net> and 150Andrew Murray <amurray@mpc-data.co.uk> 151