| If variable is of Type, use printk format specifier: |
| --------------------------------------------------------- |
| int %d or %x |
| unsigned int %u or %x |
| long %ld or %lx |
| unsigned long %lu or %lx |
| long long %lld or %llx |
| unsigned long long %llu or %llx |
| size_t %zu or %zx |
| ssize_t %zd or %zx |
| s32 %d or %x |
| u32 %u or %x |
| s64 %lld or %llx |
| u64 %llu or %llx |
| |
| If <type> is dependent on a config option for its size (e.g., sector_t, |
| blkcnt_t) or is architecture-dependent for its size (e.g., tcflag_t), use a |
| format specifier of its largest possible type and explicitly cast to it. |
| Example: |
| |
| printk("test: sector number/total blocks: %llu/%llu\n", |
| (unsigned long long)sector, (unsigned long long)blockcount); |
| |
| Reminder: sizeof() result is of type size_t. |
| |
| |
| Raw pointer value SHOULD be printed with %p. The kernel supports |
| the following extended format specifiers for pointer types: |
| |
| Symbols/Function Pointers: |
| |
| %pF versatile_init+0x0/0x110 |
| %pf versatile_init |
| %pS versatile_init+0x0/0x110 |
| %pSR versatile_init+0x9/0x110 |
| (with __builtin_extract_return_addr() translation) |
| %ps versatile_init |
| %pB prev_fn_of_versatile_init+0x88/0x88 |
| |
| For printing symbols and function pointers. The 'S' and 's' specifiers |
| result in the symbol name with ('S') or without ('s') offsets. Where |
| this is used on a kernel without KALLSYMS - the symbol address is |
| printed instead. |
| |
| The 'B' specifier results in the symbol name with offsets and should be |
| used when printing stack backtraces. The specifier takes into |
| consideration the effect of compiler optimisations which may occur |
| when tail-call's are used and marked with the noreturn GCC attribute. |
| |
| On ia64, ppc64 and parisc64 architectures function pointers are |
| actually function descriptors which must first be resolved. The 'F' and |
| 'f' specifiers perform this resolution and then provide the same |
| functionality as the 'S' and 's' specifiers. |
| |
| Kernel Pointers: |
| |
| %pK 0x01234567 or 0x0123456789abcdef |
| |
| For printing kernel pointers which should be hidden from unprivileged |
| users. The behaviour of %pK depends on the kptr_restrict sysctl - see |
| Documentation/sysctl/kernel.txt for more details. |
| |
| Struct Resources: |
| |
| %pr [mem 0x60000000-0x6fffffff flags 0x2200] or |
| [mem 0x0000000060000000-0x000000006fffffff flags 0x2200] |
| %pR [mem 0x60000000-0x6fffffff pref] or |
| [mem 0x0000000060000000-0x000000006fffffff pref] |
| |
| For printing struct resources. The 'R' and 'r' specifiers result in a |
| printed resource with ('R') or without ('r') a decoded flags member. |
| Passed by reference. |
| |
| Physical addresses types phys_addr_t: |
| |
| %pa[p] 0x01234567 or 0x0123456789abcdef |
| |
| For printing a phys_addr_t type (and its derivatives, such as |
| resource_size_t) which can vary based on build options, regardless of |
| the width of the CPU data path. Passed by reference. |
| |
| DMA addresses types dma_addr_t: |
| |
| %pad 0x01234567 or 0x0123456789abcdef |
| |
| For printing a dma_addr_t type which can vary based on build options, |
| regardless of the width of the CPU data path. Passed by reference. |
| |
| Raw buffer as an escaped string: |
| |
| %*pE[achnops] |
| |
| For printing raw buffer as an escaped string. For the following buffer |
| |
| 1b 62 20 5c 43 07 22 90 0d 5d |
| |
| few examples show how the conversion would be done (the result string |
| without surrounding quotes): |
| |
| %*pE "\eb \C\a"\220\r]" |
| %*pEhp "\x1bb \C\x07"\x90\x0d]" |
| %*pEa "\e\142\040\\\103\a\042\220\r\135" |
| |
| The conversion rules are applied according to an optional combination |
| of flags (see string_escape_mem() kernel documentation for the |
| details): |
| a - ESCAPE_ANY |
| c - ESCAPE_SPECIAL |
| h - ESCAPE_HEX |
| n - ESCAPE_NULL |
| o - ESCAPE_OCTAL |
| p - ESCAPE_NP |
| s - ESCAPE_SPACE |
| By default ESCAPE_ANY_NP is used. |
| |
| ESCAPE_ANY_NP is the sane choice for many cases, in particularly for |
| printing SSIDs. |
| |
| If field width is omitted the 1 byte only will be escaped. |
| |
| Raw buffer as a hex string: |
| %*ph 00 01 02 ... 3f |
| %*phC 00:01:02: ... :3f |
| %*phD 00-01-02- ... -3f |
| %*phN 000102 ... 3f |
| |
| For printing a small buffers (up to 64 bytes long) as a hex string with |
| certain separator. For the larger buffers consider to use |
| print_hex_dump(). |
| |
| MAC/FDDI addresses: |
| |
| %pM 00:01:02:03:04:05 |
| %pMR 05:04:03:02:01:00 |
| %pMF 00-01-02-03-04-05 |
| %pm 000102030405 |
| %pmR 050403020100 |
| |
| For printing 6-byte MAC/FDDI addresses in hex notation. The 'M' and 'm' |
| specifiers result in a printed address with ('M') or without ('m') byte |
| separators. The default byte separator is the colon (':'). |
| |
| Where FDDI addresses are concerned the 'F' specifier can be used after |
| the 'M' specifier to use dash ('-') separators instead of the default |
| separator. |
| |
| For Bluetooth addresses the 'R' specifier shall be used after the 'M' |
| specifier to use reversed byte order suitable for visual interpretation |
| of Bluetooth addresses which are in the little endian order. |
| |
| Passed by reference. |
| |
| IPv4 addresses: |
| |
| %pI4 1.2.3.4 |
| %pi4 001.002.003.004 |
| %p[Ii]4[hnbl] |
| |
| For printing IPv4 dot-separated decimal addresses. The 'I4' and 'i4' |
| specifiers result in a printed address with ('i4') or without ('I4') |
| leading zeros. |
| |
| The additional 'h', 'n', 'b', and 'l' specifiers are used to specify |
| host, network, big or little endian order addresses respectively. Where |
| no specifier is provided the default network/big endian order is used. |
| |
| Passed by reference. |
| |
| IPv6 addresses: |
| |
| %pI6 0001:0002:0003:0004:0005:0006:0007:0008 |
| %pi6 00010002000300040005000600070008 |
| %pI6c 1:2:3:4:5:6:7:8 |
| |
| For printing IPv6 network-order 16-bit hex addresses. The 'I6' and 'i6' |
| specifiers result in a printed address with ('I6') or without ('i6') |
| colon-separators. Leading zeros are always used. |
| |
| The additional 'c' specifier can be used with the 'I' specifier to |
| print a compressed IPv6 address as described by |
| http://tools.ietf.org/html/rfc5952 |
| |
| Passed by reference. |
| |
| IPv4/IPv6 addresses (generic, with port, flowinfo, scope): |
| |
| %pIS 1.2.3.4 or 0001:0002:0003:0004:0005:0006:0007:0008 |
| %piS 001.002.003.004 or 00010002000300040005000600070008 |
| %pISc 1.2.3.4 or 1:2:3:4:5:6:7:8 |
| %pISpc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345 |
| %p[Ii]S[pfschnbl] |
| |
| For printing an IP address without the need to distinguish whether it's |
| of type AF_INET or AF_INET6, a pointer to a valid 'struct sockaddr', |
| specified through 'IS' or 'iS', can be passed to this format specifier. |
| |
| The additional 'p', 'f', and 's' specifiers are used to specify port |
| (IPv4, IPv6), flowinfo (IPv6) and scope (IPv6). Ports have a ':' prefix, |
| flowinfo a '/' and scope a '%', each followed by the actual value. |
| |
| In case of an IPv6 address the compressed IPv6 address as described by |
| http://tools.ietf.org/html/rfc5952 is being used if the additional |
| specifier 'c' is given. The IPv6 address is surrounded by '[', ']' in |
| case of additional specifiers 'p', 'f' or 's' as suggested by |
| https://tools.ietf.org/html/draft-ietf-6man-text-addr-representation-07 |
| |
| In case of IPv4 addresses, the additional 'h', 'n', 'b', and 'l' |
| specifiers can be used as well and are ignored in case of an IPv6 |
| address. |
| |
| Passed by reference. |
| |
| Further examples: |
| |
| %pISfc 1.2.3.4 or [1:2:3:4:5:6:7:8]/123456789 |
| %pISsc 1.2.3.4 or [1:2:3:4:5:6:7:8]%1234567890 |
| %pISpfc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345/123456789 |
| |
| UUID/GUID addresses: |
| |
| %pUb 00010203-0405-0607-0809-0a0b0c0d0e0f |
| %pUB 00010203-0405-0607-0809-0A0B0C0D0E0F |
| %pUl 03020100-0504-0706-0809-0a0b0c0e0e0f |
| %pUL 03020100-0504-0706-0809-0A0B0C0E0E0F |
| |
| For printing 16-byte UUID/GUIDs addresses. The additional 'l', 'L', |
| 'b' and 'B' specifiers are used to specify a little endian order in |
| lower ('l') or upper case ('L') hex characters - and big endian order |
| in lower ('b') or upper case ('B') hex characters. |
| |
| Where no additional specifiers are used the default big endian |
| order with lower case hex characters will be printed. |
| |
| Passed by reference. |
| |
| dentry names: |
| %pd{,2,3,4} |
| %pD{,2,3,4} |
| |
| For printing dentry name; if we race with d_move(), the name might be |
| a mix of old and new ones, but it won't oops. %pd dentry is a safer |
| equivalent of %s dentry->d_name.name we used to use, %pd<n> prints |
| n last components. %pD does the same thing for struct file. |
| |
| Passed by reference. |
| |
| struct va_format: |
| |
| %pV |
| |
| For printing struct va_format structures. These contain a format string |
| and va_list as follows: |
| |
| struct va_format { |
| const char *fmt; |
| va_list *va; |
| }; |
| |
| Do not use this feature without some mechanism to verify the |
| correctness of the format string and va_list arguments. |
| |
| Passed by reference. |
| |
| struct clk: |
| |
| %pC pll1 |
| %pCn pll1 |
| %pCr 1560000000 |
| |
| For printing struct clk structures. '%pC' and '%pCn' print the name |
| (Common Clock Framework) or address (legacy clock framework) of the |
| structure; '%pCr' prints the current clock rate. |
| |
| Passed by reference. |
| |
| bitmap and its derivatives such as cpumask and nodemask: |
| |
| %*pb 0779 |
| %*pbl 0,3-6,8-10 |
| |
| For printing bitmap and its derivatives such as cpumask and nodemask, |
| %*pb output the bitmap with field width as the number of bits and %*pbl |
| output the bitmap as range list with field width as the number of bits. |
| |
| Passed by reference. |
| |
| Thank you for your cooperation and attention. |
| |
| |
| By Randy Dunlap <rdunlap@infradead.org> and |
| Andrew Murray <amurray@mpc-data.co.uk> |