forked from Minki/linux
d181b71c3e
The documentation and the code disagrees; fix the former. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
266 lines
8.6 KiB
Plaintext
266 lines
8.6 KiB
Plaintext
If variable is of Type, use printk format specifier:
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---------------------------------------------------------
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int %d or %x
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unsigned int %u or %x
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long %ld or %lx
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unsigned long %lu or %lx
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long long %lld or %llx
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unsigned long long %llu or %llx
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size_t %zu or %zx
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ssize_t %zd or %zx
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Raw pointer value SHOULD be printed with %p. The kernel supports
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the following extended format specifiers for pointer types:
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Symbols/Function Pointers:
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%pF versatile_init+0x0/0x110
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%pf versatile_init
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%pS versatile_init+0x0/0x110
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%pSR versatile_init+0x9/0x110
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(with __builtin_extract_return_addr() translation)
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%ps versatile_init
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%pB prev_fn_of_versatile_init+0x88/0x88
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For printing symbols and function pointers. The 'S' and 's' specifiers
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result in the symbol name with ('S') or without ('s') offsets. Where
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this is used on a kernel without KALLSYMS - the symbol address is
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printed instead.
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The 'B' specifier results in the symbol name with offsets and should be
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used when printing stack backtraces. The specifier takes into
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consideration the effect of compiler optimisations which may occur
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when tail-call's are used and marked with the noreturn GCC attribute.
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On ia64, ppc64 and parisc64 architectures function pointers are
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actually function descriptors which must first be resolved. The 'F' and
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'f' specifiers perform this resolution and then provide the same
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functionality as the 'S' and 's' specifiers.
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Kernel Pointers:
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%pK 0x01234567 or 0x0123456789abcdef
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For printing kernel pointers which should be hidden from unprivileged
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users. The behaviour of %pK depends on the kptr_restrict sysctl - see
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Documentation/sysctl/kernel.txt for more details.
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Struct Resources:
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%pr [mem 0x60000000-0x6fffffff flags 0x2200] or
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[mem 0x0000000060000000-0x000000006fffffff flags 0x2200]
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%pR [mem 0x60000000-0x6fffffff pref] or
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[mem 0x0000000060000000-0x000000006fffffff pref]
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For printing struct resources. The 'R' and 'r' specifiers result in a
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printed resource with ('R') or without ('r') a decoded flags member.
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Physical addresses types phys_addr_t:
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%pa[p] 0x01234567 or 0x0123456789abcdef
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For printing a phys_addr_t type (and its derivatives, such as
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resource_size_t) which can vary based on build options, regardless of
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the width of the CPU data path. Passed by reference.
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DMA addresses types dma_addr_t:
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%pad 0x01234567 or 0x0123456789abcdef
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For printing a dma_addr_t type which can vary based on build options,
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regardless of the width of the CPU data path. Passed by reference.
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Raw buffer as an escaped string:
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%*pE[achnops]
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For printing raw buffer as an escaped string. For the following buffer
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1b 62 20 5c 43 07 22 90 0d 5d
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few examples show how the conversion would be done (the result string
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without surrounding quotes):
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%*pE "\eb \C\a"\220\r]"
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%*pEhp "\x1bb \C\x07"\x90\x0d]"
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%*pEa "\e\142\040\\\103\a\042\220\r\135"
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The conversion rules are applied according to an optional combination
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of flags (see string_escape_mem() kernel documentation for the
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details):
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a - ESCAPE_ANY
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c - ESCAPE_SPECIAL
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h - ESCAPE_HEX
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n - ESCAPE_NULL
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o - ESCAPE_OCTAL
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p - ESCAPE_NP
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s - ESCAPE_SPACE
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By default ESCAPE_ANY_NP is used.
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ESCAPE_ANY_NP is the sane choice for many cases, in particularly for
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printing SSIDs.
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If field width is omitted the 1 byte only will be escaped.
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Raw buffer as a hex string:
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%*ph 00 01 02 ... 3f
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%*phC 00:01:02: ... :3f
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%*phD 00-01-02- ... -3f
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%*phN 000102 ... 3f
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For printing a small buffers (up to 64 bytes long) as a hex string with
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certain separator. For the larger buffers consider to use
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print_hex_dump().
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MAC/FDDI addresses:
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%pM 00:01:02:03:04:05
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%pMR 05:04:03:02:01:00
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%pMF 00-01-02-03-04-05
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%pm 000102030405
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%pmR 050403020100
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For printing 6-byte MAC/FDDI addresses in hex notation. The 'M' and 'm'
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specifiers result in a printed address with ('M') or without ('m') byte
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separators. The default byte separator is the colon (':').
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Where FDDI addresses are concerned the 'F' specifier can be used after
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the 'M' specifier to use dash ('-') separators instead of the default
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separator.
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For Bluetooth addresses the 'R' specifier shall be used after the 'M'
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specifier to use reversed byte order suitable for visual interpretation
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of Bluetooth addresses which are in the little endian order.
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IPv4 addresses:
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%pI4 1.2.3.4
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%pi4 001.002.003.004
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%p[Ii]4[hnbl]
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For printing IPv4 dot-separated decimal addresses. The 'I4' and 'i4'
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specifiers result in a printed address with ('i4') or without ('I4')
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leading zeros.
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The additional 'h', 'n', 'b', and 'l' specifiers are used to specify
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host, network, big or little endian order addresses respectively. Where
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no specifier is provided the default network/big endian order is used.
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IPv6 addresses:
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%pI6 0001:0002:0003:0004:0005:0006:0007:0008
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%pi6 00010002000300040005000600070008
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%pI6c 1:2:3:4:5:6:7:8
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For printing IPv6 network-order 16-bit hex addresses. The 'I6' and 'i6'
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specifiers result in a printed address with ('I6') or without ('i6')
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colon-separators. Leading zeros are always used.
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The additional 'c' specifier can be used with the 'I' specifier to
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print a compressed IPv6 address as described by
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http://tools.ietf.org/html/rfc5952
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IPv4/IPv6 addresses (generic, with port, flowinfo, scope):
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%pIS 1.2.3.4 or 0001:0002:0003:0004:0005:0006:0007:0008
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%piS 001.002.003.004 or 00010002000300040005000600070008
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%pISc 1.2.3.4 or 1:2:3:4:5:6:7:8
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%pISpc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345
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%p[Ii]S[pfschnbl]
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For printing an IP address without the need to distinguish whether it's
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of type AF_INET or AF_INET6, a pointer to a valid 'struct sockaddr',
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specified through 'IS' or 'iS', can be passed to this format specifier.
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The additional 'p', 'f', and 's' specifiers are used to specify port
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(IPv4, IPv6), flowinfo (IPv6) and scope (IPv6). Ports have a ':' prefix,
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flowinfo a '/' and scope a '%', each followed by the actual value.
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In case of an IPv6 address the compressed IPv6 address as described by
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http://tools.ietf.org/html/rfc5952 is being used if the additional
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specifier 'c' is given. The IPv6 address is surrounded by '[', ']' in
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case of additional specifiers 'p', 'f' or 's' as suggested by
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https://tools.ietf.org/html/draft-ietf-6man-text-addr-representation-07
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In case of IPv4 addresses, the additional 'h', 'n', 'b', and 'l'
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specifiers can be used as well and are ignored in case of an IPv6
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address.
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Further examples:
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%pISfc 1.2.3.4 or [1:2:3:4:5:6:7:8]/123456789
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%pISsc 1.2.3.4 or [1:2:3:4:5:6:7:8]%1234567890
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%pISpfc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345/123456789
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UUID/GUID addresses:
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%pUb 00010203-0405-0607-0809-0a0b0c0d0e0f
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%pUB 00010203-0405-0607-0809-0A0B0C0D0E0F
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%pUl 03020100-0504-0706-0809-0a0b0c0e0e0f
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%pUL 03020100-0504-0706-0809-0A0B0C0E0E0F
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For printing 16-byte UUID/GUIDs addresses. The additional 'l', 'L',
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'b' and 'B' specifiers are used to specify a little endian order in
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lower ('l') or upper case ('L') hex characters - and big endian order
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in lower ('b') or upper case ('B') hex characters.
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Where no additional specifiers are used the default big endian
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order with lower case hex characters will be printed.
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dentry names:
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%pd{,2,3,4}
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%pD{,2,3,4}
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For printing dentry name; if we race with d_move(), the name might be
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a mix of old and new ones, but it won't oops. %pd dentry is a safer
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equivalent of %s dentry->d_name.name we used to use, %pd<n> prints
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n last components. %pD does the same thing for struct file.
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struct va_format:
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%pV
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For printing struct va_format structures. These contain a format string
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and va_list as follows:
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struct va_format {
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const char *fmt;
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va_list *va;
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};
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Do not use this feature without some mechanism to verify the
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correctness of the format string and va_list arguments.
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u64 SHOULD be printed with %llu/%llx:
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printk("%llu", u64_var);
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s64 SHOULD be printed with %lld/%llx:
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printk("%lld", s64_var);
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bitmap and its derivatives such as cpumask and nodemask:
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%*pb 0779
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%*pbl 0,3-6,8-10
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For printing bitmap and its derivatives such as cpumask and nodemask,
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%*pb output the bitmap with field width as the number of bits and %*pbl
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output the bitmap as range list with field width as the number of bits.
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If <type> is dependent on a config option for its size (e.g., sector_t,
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blkcnt_t) or is architecture-dependent for its size (e.g., tcflag_t), use a
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format specifier of its largest possible type and explicitly cast to it.
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Example:
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printk("test: sector number/total blocks: %llu/%llu\n",
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(unsigned long long)sector, (unsigned long long)blockcount);
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Reminder: sizeof() result is of type size_t.
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Thank you for your cooperation and attention.
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By Randy Dunlap <rdunlap@infradead.org> and
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Andrew Murray <amurray@mpc-data.co.uk>
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