[apple/xnu.git] / bsd / man / man9 / intro.9

.\" Copyright (c) 1983, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD: src/share/man/man9/intro.9,v 1.15 2001/07/14 19:41:16 schweikh Exp $
.\"
.Dd December 13, 1995
.Dt INTRO 9
.Os
.Sh NAME
.Nm intro
.Nd "introduction to system kernel interfaces"
.Sh DESCRIPTION
This section contains information about the interfaces and
subroutines in the kernel.
.Sh PROTOTYPES ANSI-C AND ALL THAT
Yes please.
.Pp
We would like all code to be fully prototyped.
.Pp
If your code compiles cleanly with
.Nm cc
.Ar -Wall
we would feel happy about it.
It is important to understand that this isn't a question of just shutting up
.Nm cc ,
it is a question about avoiding the things it complains about.
To put it bluntly, don't hide the problem by casting and other
obfuscating practices, solve the problem.
.Sh INDENTATION AND STYLE
Believe it or not, there actually exists a guide for indentation and style.
It isn't generally applied though.
.Pp
We would appreciate if people would pay attention to it, and at least not
violate it blatantly.
.Pp
We don't mind it too badly if you have your own style, but please make
sure we can read it too.
.Pp
Please take time to read
.Xr style 9
for more information.
.Sh NAMING THINGS
Some general rules exist:
.Bl -enum
.It
If a function is meant as a debugging aid in DDB, it should be enclosed
in
.Bd -literal -offset indent
#ifdef DDB

#endif /* DDB */
.Ed
.Pp
And the name of the procedure should start with the prefix
.Li DDB_
to clearly identify the procedure as a debugger routine.
.El
.Sh SCOPE OF SYMBOLS
It is important to carefully consider the scope of symbols in the kernel.
The default is to make everything static, unless some reason requires
the opposite.
.Pp
There are several reasons for this policy,
the main one is that the kernel is one monolithic name-space,
and pollution is not a good idea here either.
.Pp
For device drivers and other modules that don't add new internal interfaces
to the kernel, the entire source should be in one file if possible.
That way all symbols can be made static.
.Pp
If for some reason a module is split over multiple source files, then try
to split the module along some major fault-line and consider using the
number of global symbols as your guide.
The fewer the better.
.Sh SEE ALSO
.Xr style 9
.Sh HISTORY
The
.Nm
section manual page appeared in
.Fx 2.2 .
Commit	Line	Data
55e303ae A	1	.\" Copyright (c) 1983, 1991, 1993
	2	.\" The Regents of the University of California. All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 3. All advertising materials mentioning features or use of this software
	13	.\" must display the following acknowledgement:
	14	.\" This product includes software developed by the University of
	15	.\" California, Berkeley and its contributors.
	16	.\" 4. Neither the name of the University nor the names of its contributors
	17	.\" may be used to endorse or promote products derived from this software
	18	.\" without specific prior written permission.
	19	.\"
	20	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	.\" SUCH DAMAGE.
	31	.\"
	32	.\" $FreeBSD: src/share/man/man9/intro.9,v 1.15 2001/07/14 19:41:16 schweikh Exp $
	33	.\"
	34	.Dd December 13, 1995
	35	.Dt INTRO 9
	36	.Os
	37	.Sh NAME
	38	.Nm intro
	39	.Nd "introduction to system kernel interfaces"
	40	.Sh DESCRIPTION
	41	This section contains information about the interfaces and
	42	subroutines in the kernel.
	43	.Sh PROTOTYPES ANSI-C AND ALL THAT
	44	Yes please.
	45	.Pp
	46	We would like all code to be fully prototyped.
	47	.Pp
	48	If your code compiles cleanly with
	49	.Nm cc
	50	.Ar -Wall
	51	we would feel happy about it.
	52	It is important to understand that this isn't a question of just shutting up
	53	.Nm cc ,
	54	it is a question about avoiding the things it complains about.
	55	To put it bluntly, don't hide the problem by casting and other
	56	obfuscating practices, solve the problem.
	57	.Sh INDENTATION AND STYLE
	58	Believe it or not, there actually exists a guide for indentation and style.
	59	It isn't generally applied though.
	60	.Pp
	61	We would appreciate if people would pay attention to it, and at least not
	62	violate it blatantly.
	63	.Pp
	64	We don't mind it too badly if you have your own style, but please make
65	sure we can read it too.
66	.Pp
67	Please take time to read
68	.Xr style 9
69	for more information.
70	.Sh NAMING THINGS
71	Some general rules exist:
72	.Bl -enum
73	.It
74	If a function is meant as a debugging aid in DDB, it should be enclosed
75	in
76	.Bd -literal -offset indent
77	#ifdef DDB
78
79	#endif /* DDB */
80	.Ed
81	.Pp
82	And the name of the procedure should start with the prefix
83	.Li DDB_
84	to clearly identify the procedure as a debugger routine.
85	.El
86	.Sh SCOPE OF SYMBOLS
87	It is important to carefully consider the scope of symbols in the kernel.
88	The default is to make everything static, unless some reason requires
89	the opposite.
90	.Pp
91	There are several reasons for this policy,
92	the main one is that the kernel is one monolithic name-space,
93	and pollution is not a good idea here either.
94	.Pp
95	For device drivers and other modules that don't add new internal interfaces
96	to the kernel, the entire source should be in one file if possible.
97	That way all symbols can be made static.
98	.Pp
99	If for some reason a module is split over multiple source files, then try
100	to split the module along some major fault-line and consider using the
101	number of global symbols as your guide.
102	The fewer the better.
103	.Sh SEE ALSO
104	.Xr style 9
105	.Sh HISTORY
106	The
107	.Nm
108	section manual page appeared in
109	.Fx 2.2 .