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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /Documentation/printk-formats.txt
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+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>