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