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		s32			%d or %x
12		u32			%u or %x
13		s64			%lld or %llx
14		u64			%llu or %llx
15
16If <type> is dependent on a config option for its size (e.g., sector_t,
17blkcnt_t) or is architecture-dependent for its size (e.g., tcflag_t), use a
18format specifier of its largest possible type and explicitly cast to it.
19Example:
20
21	printk("test: sector number/total blocks: %llu/%llu\n",
22		(unsigned long long)sector, (unsigned long long)blockcount);
23
24Reminder: sizeof() result is of type size_t.
25
26
27Raw pointer value SHOULD be printed with %p. The kernel supports
28the following extended format specifiers for pointer types:
29
30Symbols/Function Pointers:
31
32	%pF	versatile_init+0x0/0x110
33	%pf	versatile_init
34	%pS	versatile_init+0x0/0x110
35	%pSR	versatile_init+0x9/0x110
36		(with __builtin_extract_return_addr() translation)
37	%ps	versatile_init
38	%pB	prev_fn_of_versatile_init+0x88/0x88
39
40	For printing symbols and function pointers. The 'S' and 's' specifiers
41	result in the symbol name with ('S') or without ('s') offsets. Where
42	this is used on a kernel without KALLSYMS - the symbol address is
43	printed instead.
44
45	The 'B' specifier results in the symbol name with offsets and should be
46	used when printing stack backtraces. The specifier takes into
47	consideration the effect of compiler optimisations which may occur
48	when tail-call's are used and marked with the noreturn GCC attribute.
49
50	On ia64, ppc64 and parisc64 architectures function pointers are
51	actually function descriptors which must first be resolved. The 'F' and
52	'f' specifiers perform this resolution and then provide the same
53	functionality as the 'S' and 's' specifiers.
54
55Kernel Pointers:
56
57	%pK	0x01234567 or 0x0123456789abcdef
58
59	For printing kernel pointers which should be hidden from unprivileged
60	users. The behaviour of %pK depends on the kptr_restrict sysctl - see
61	Documentation/sysctl/kernel.txt for more details.
62
63Struct Resources:
64
65	%pr	[mem 0x60000000-0x6fffffff flags 0x2200] or
66		[mem 0x0000000060000000-0x000000006fffffff flags 0x2200]
67	%pR	[mem 0x60000000-0x6fffffff pref] or
68		[mem 0x0000000060000000-0x000000006fffffff pref]
69
70	For printing struct resources. The 'R' and 'r' specifiers result in a
71	printed resource with ('R') or without ('r') a decoded flags member.
72	Passed by reference.
73
74Physical addresses types phys_addr_t:
75
76	%pa[p]	0x01234567 or 0x0123456789abcdef
77
78	For printing a phys_addr_t type (and its derivatives, such as
79	resource_size_t) which can vary based on build options, regardless of
80	the width of the CPU data path. Passed by reference.
81
82DMA addresses types dma_addr_t:
83
84	%pad	0x01234567 or 0x0123456789abcdef
85
86	For printing a dma_addr_t type which can vary based on build options,
87	regardless of the width of the CPU data path. Passed by reference.
88
89Raw buffer as an escaped string:
90
91	%*pE[achnops]
92
93	For printing raw buffer as an escaped string. For the following buffer
94
95		1b 62 20 5c 43 07 22 90 0d 5d
96
97	few examples show how the conversion would be done (the result string
98	without surrounding quotes):
99
100		%*pE		"\eb \C\a"\220\r]"
101		%*pEhp		"\x1bb \C\x07"\x90\x0d]"
102		%*pEa		"\e\142\040\\\103\a\042\220\r\135"
103
104	The conversion rules are applied according to an optional combination
105	of flags (see string_escape_mem() kernel documentation for the
106	details):
107		a - ESCAPE_ANY
108		c - ESCAPE_SPECIAL
109		h - ESCAPE_HEX
110		n - ESCAPE_NULL
111		o - ESCAPE_OCTAL
112		p - ESCAPE_NP
113		s - ESCAPE_SPACE
114	By default ESCAPE_ANY_NP is used.
115
116	ESCAPE_ANY_NP is the sane choice for many cases, in particularly for
117	printing SSIDs.
118
119	If field width is omitted the 1 byte only will be escaped.
120
121Raw buffer as a hex string:
122	%*ph	00 01 02  ...  3f
123	%*phC	00:01:02: ... :3f
124	%*phD	00-01-02- ... -3f
125	%*phN	000102 ... 3f
126
127	For printing a small buffers (up to 64 bytes long) as a hex string with
128	certain separator. For the larger buffers consider to use
129	print_hex_dump().
130
131MAC/FDDI addresses:
132
133	%pM	00:01:02:03:04:05
134	%pMR	05:04:03:02:01:00
135	%pMF	00-01-02-03-04-05
136	%pm	000102030405
137	%pmR	050403020100
138
139	For printing 6-byte MAC/FDDI addresses in hex notation. The 'M' and 'm'
140	specifiers result in a printed address with ('M') or without ('m') byte
141	separators. The default byte separator is the colon (':').
142
143	Where FDDI addresses are concerned the 'F' specifier can be used after
144	the 'M' specifier to use dash ('-') separators instead of the default
145	separator.
146
147	For Bluetooth addresses the 'R' specifier shall be used after the 'M'
148	specifier to use reversed byte order suitable for visual interpretation
149	of Bluetooth addresses which are in the little endian order.
150
151	Passed by reference.
152
153IPv4 addresses:
154
155	%pI4	1.2.3.4
156	%pi4	001.002.003.004
157	%p[Ii]4[hnbl]
158
159	For printing IPv4 dot-separated decimal addresses. The 'I4' and 'i4'
160	specifiers result in a printed address with ('i4') or without ('I4')
161	leading zeros.
162
163	The additional 'h', 'n', 'b', and 'l' specifiers are used to specify
164	host, network, big or little endian order addresses respectively. Where
165	no specifier is provided the default network/big endian order is used.
166
167	Passed by reference.
168
169IPv6 addresses:
170
171	%pI6	0001:0002:0003:0004:0005:0006:0007:0008
172	%pi6	00010002000300040005000600070008
173	%pI6c	1:2:3:4:5:6:7:8
174
175	For printing IPv6 network-order 16-bit hex addresses. The 'I6' and 'i6'
176	specifiers result in a printed address with ('I6') or without ('i6')
177	colon-separators. Leading zeros are always used.
178
179	The additional 'c' specifier can be used with the 'I' specifier to
180	print a compressed IPv6 address as described by
181	http://tools.ietf.org/html/rfc5952
182
183	Passed by reference.
184
185IPv4/IPv6 addresses (generic, with port, flowinfo, scope):
186
187	%pIS	1.2.3.4		or 0001:0002:0003:0004:0005:0006:0007:0008
188	%piS	001.002.003.004	or 00010002000300040005000600070008
189	%pISc	1.2.3.4		or 1:2:3:4:5:6:7:8
190	%pISpc	1.2.3.4:12345	or [1:2:3:4:5:6:7:8]:12345
191	%p[Ii]S[pfschnbl]
192
193	For printing an IP address without the need to distinguish whether it's
194	of type AF_INET or AF_INET6, a pointer to a valid 'struct sockaddr',
195	specified through 'IS' or 'iS', can be passed to this format specifier.
196
197	The additional 'p', 'f', and 's' specifiers are used to specify port
198	(IPv4, IPv6), flowinfo (IPv6) and scope (IPv6). Ports have a ':' prefix,
199	flowinfo a '/' and scope a '%', each followed by the actual value.
200
201	In case of an IPv6 address the compressed IPv6 address as described by
202	http://tools.ietf.org/html/rfc5952 is being used if the additional
203	specifier 'c' is given. The IPv6 address is surrounded by '[', ']' in
204	case of additional specifiers 'p', 'f' or 's' as suggested by
205	https://tools.ietf.org/html/draft-ietf-6man-text-addr-representation-07
206
207	In case of IPv4 addresses, the additional 'h', 'n', 'b', and 'l'
208	specifiers can be used as well and are ignored in case of an IPv6
209	address.
210
211	Passed by reference.
212
213	Further examples:
214
215	%pISfc		1.2.3.4		or [1:2:3:4:5:6:7:8]/123456789
216	%pISsc		1.2.3.4		or [1:2:3:4:5:6:7:8]%1234567890
217	%pISpfc		1.2.3.4:12345	or [1:2:3:4:5:6:7:8]:12345/123456789
218
219UUID/GUID addresses:
220
221	%pUb	00010203-0405-0607-0809-0a0b0c0d0e0f
222	%pUB	00010203-0405-0607-0809-0A0B0C0D0E0F
223	%pUl	03020100-0504-0706-0809-0a0b0c0e0e0f
224	%pUL	03020100-0504-0706-0809-0A0B0C0E0E0F
225
226	For printing 16-byte UUID/GUIDs addresses. The additional 'l', 'L',
227	'b' and 'B' specifiers are used to specify a little endian order in
228	lower ('l') or upper case ('L') hex characters - and big endian order
229	in lower ('b') or upper case ('B') hex characters.
230
231	Where no additional specifiers are used the default big endian
232	order with lower case hex characters will be printed.
233
234	Passed by reference.
235
236dentry names:
237	%pd{,2,3,4}
238	%pD{,2,3,4}
239
240	For printing dentry name; if we race with d_move(), the name might be
241	a mix of old and new ones, but it won't oops.  %pd dentry is a safer
242	equivalent of %s dentry->d_name.name we used to use, %pd<n> prints
243	n last components.  %pD does the same thing for struct file.
244
245	Passed by reference.
246
247struct va_format:
248
249	%pV
250
251	For printing struct va_format structures. These contain a format string
252	and va_list as follows:
253
254	struct va_format {
255		const char *fmt;
256		va_list *va;
257	};
258
259	Do not use this feature without some mechanism to verify the
260	correctness of the format string and va_list arguments.
261
262	Passed by reference.
263
264struct clk:
265
266	%pC	pll1
267	%pCn	pll1
268	%pCr	1560000000
269
270	For printing struct clk structures. '%pC' and '%pCn' print the name
271	(Common Clock Framework) or address (legacy clock framework) of the
272	structure; '%pCr' prints the current clock rate.
273
274	Passed by reference.
275
276bitmap and its derivatives such as cpumask and nodemask:
277
278	%*pb	0779
279	%*pbl	0,3-6,8-10
280
281	For printing bitmap and its derivatives such as cpumask and nodemask,
282	%*pb output the bitmap with field width as the number of bits and %*pbl
283	output the bitmap as range list with field width as the number of bits.
284
285	Passed by reference.
286
287Thank you for your cooperation and attention.
288
289
290By Randy Dunlap <rdunlap@infradead.org> and
291Andrew Murray <amurray@mpc-data.co.uk>
292