printk-formats.txt: standardize document format

Each text file under Documentation follows a different
format. Some doesn't even have titles!

Change its representation to follow the adopted standard,
using ReST markups for it to be parseable by Sphinx:

- add a title for the document;
- add markups for section titles;
- move authorship to the beginning and use :Author:;
- use right markup for tables;
- mark literals and literal blocks.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/printk-formats.txt

-If variable is of Type,		use printk format specifier:
----------------------------------------------------------
+=========================================
+How to get printk format specifiers right
+=========================================
+
+:Author: Randy Dunlap <rdunlap@infradead.org>
+:Author: Andrew Murray <amurray@mpc-data.co.uk>
+
+
+Integer types
+=============
+
+::
+
+	If variable is of Type,		use printk format specifier:
+	------------------------------------------------------------
 		int			%d or %x
 		unsigned int		%u or %x
 		long			%ld or %lx
@@ -13,25 +26,29 @@ If variable is of Type,		use printk format specifier:
 		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:
+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.
+Reminder: ``sizeof()`` result is of type ``size_t``.
 
-The kernel's printf does not support %n. For obvious reasons, floating
-point formats (%e, %f, %g, %a) are also not recognized. Use of any
+The kernel's printf does not support ``%n``. For obvious reasons, floating
+point formats (``%e, %f, %g, %a``) are also not recognized. Use of any
 unsupported specifier or length qualifier results in a WARN and early
 return from vsnprintf.
 
 Raw pointer value SHOULD be printed with %p. The kernel supports
 the following extended format specifiers for pointer types:
 
-Symbols/Function Pointers:
+Symbols/Function Pointers
+=========================
+
+::
 
 	%pF	versatile_init+0x0/0x110
 	%pf	versatile_init
@@ -41,99 +58,122 @@ Symbols/Function Pointers:
 	%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.
+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.
 
-	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.
 
-	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
+===============
 
-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.
+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
+================
 
-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.
+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``
+========================================
 
-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.
+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:
+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.
+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
+===============================
 
-Raw buffer as an escaped string:
+::
 
 	%*pE[achnops]
 
-	For printing raw buffer as an escaped string. For the following buffer
+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):
+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.
+The conversion rules are applied according to an optional combination
+of flags (see :c:func:`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
 
-	ESCAPE_ANY_NP is the sane choice for many cases, in particularly for
-	printing SSIDs.
+By default ESCAPE_ANY_NP is used.
 
-	If field width is omitted the 1 byte only will be escaped.
+ESCAPE_ANY_NP is the sane choice for many cases, in particularly for
+printing SSIDs.
 
-Raw buffer as a hex string:
+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().
+For printing a small buffers (up to 64 bytes long) as a hex string with
+certain separator. For the larger buffers consider to use
+:c:func:`print_hex_dump`.
+
+MAC/FDDI addresses
+==================
 
-MAC/FDDI addresses:
+::
 
 	%pM	00:01:02:03:04:05
 	%pMR	05:04:03:02:01:00
@@ -141,53 +181,62 @@ MAC/FDDI addresses:
 	%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 (':').
+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.
+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.
+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.
+Passed by reference.
+
+IPv4 addresses
+==============
 
-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.
+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.
+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.
+Passed by reference.
 
-IPv6 addresses:
+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.
+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
+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.
+Passed by reference.
 
-IPv4/IPv6 addresses (generic, with port, flowinfo, scope):
+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
@@ -195,87 +244,103 @@ IPv4/IPv6 addresses (generic, with port, flowinfo, scope):
 	%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.
+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.
+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 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.
+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.
+Passed by reference.
 
-	Further examples:
+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:
+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.
+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.
+Where no additional specifiers are used the default big endian
+order with lower case hex characters will be printed.
 
-	Passed by reference.
+Passed by reference.
+
+dentry names
+============
 
-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.
+For printing dentry name; if we race with :c:func:`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.
+Passed by reference.
 
-block_device names:
+block_device names
+==================
+
+::
 
 	%pg	sda, sda1 or loop0p1
 
-	For printing name of block_device pointers.
+For printing name of block_device pointers.
+
+struct va_format
+================
 
-struct va_format:
+::
 
 	%pV
 
-	For printing struct va_format structures. These contain a format string
-	and va_list as follows:
+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;
 	};
 
-	Implements a "recursive vsnprintf".
+Implements a "recursive vsnprintf".
 
-	Do not use this feature without some mechanism to verify the
-	correctness of the format string and va_list arguments.
+Do not use this feature without some mechanism to verify the
+correctness of the format string and va_list arguments.
 
-	Passed by reference.
+Passed by reference.
+
+kobjects
+========
+
+::
 
-kobjects:
 	%pO
 
 	Base specifier for kobject based structs. Must be followed with
@@ -311,61 +376,70 @@ kobjects:
 
 	Passed by reference.
 
-struct clk:
+
+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.
+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.
+Passed by reference.
 
-bitmap and its derivatives such as cpumask and nodemask:
+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.
+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.
+Passed by reference.
+
+Flags bitfields such as page flags, gfp_flags
+=============================================
 
-Flags bitfields such as page flags, gfp_flags:
+::
 
 	%pGp	referenced|uptodate|lru|active|private
 	%pGg	GFP_USER|GFP_DMA32|GFP_NOWARN
 	%pGv	read|exec|mayread|maywrite|mayexec|denywrite
 
-	For printing flags bitfields as a collection of symbolic constants that
-	would construct the value. The type of flags is given by the third
-	character. Currently supported are [p]age flags, [v]ma_flags (both
-	expect unsigned long *) and [g]fp_flags (expects gfp_t *). The flag
-	names and print order depends on the particular	type.
+For printing flags bitfields as a collection of symbolic constants that
+would construct the value. The type of flags is given by the third
+character. Currently supported are [p]age flags, [v]ma_flags (both
+expect ``unsigned long *``) and [g]fp_flags (expects ``gfp_t *``). The flag
+names and print order depends on the particular	type.
 
-	Note that this format should not be used directly in TP_printk() part
-	of a tracepoint. Instead, use the show_*_flags() functions from
-	<trace/events/mmflags.h>.
+Note that this format should not be used directly in :c:func:`TP_printk()` part
+of a tracepoint. Instead, use the ``show_*_flags()`` functions from
+<trace/events/mmflags.h>.
 
-	Passed by reference.
+Passed by reference.
+
+Network device features
+=======================
 
-Network device features:
+::
 
 	%pNF	0x000000000000c000
 
-	For printing netdev_features_t.
+For printing netdev_features_t.
 
-	Passed by reference.
+Passed by reference.
 
-If you add other %p extensions, please extend lib/test_printf.c with
+If you add other ``%p`` extensions, please extend lib/test_printf.c with
 one or more test cases, if at all feasible.
 
 
 Thank you for your cooperation and attention.
-
-
-By Randy Dunlap <rdunlap@infradead.org> and
-Andrew Murray <amurray@mpc-data.co.uk>