1.\" Copyright (c) 1992, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software developed by the Computer Systems 5.\" Engineering group at Lawrence Berkeley Laboratory under DARPA contract 6.\" BG 91-66 and contributed to Berkeley. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 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.\" @(#)kvm.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD$ 34.\" 35.Dd January 29, 2004 36.Dt KVM 3 37.Os 38.Sh NAME 39.Nm kvm 40.Nd kernel memory interface 41.Sh LIBRARY 42.Lb libkvm 43.Sh DESCRIPTION 44The 45.Nm 46library provides a uniform interface for accessing kernel virtual memory 47images, including live systems and crash dumps. 48Access to live systems is via 49.Xr mem 4 50and 51.Xr kmem 4 52while crash dumps can be examined via the core file generated by 53.Xr savecore 8 . 54The interface behaves identically in both cases. 55Memory can be read and written, kernel symbol addresses can be 56looked up efficiently, and information about user processes can 57be gathered. 58.Pp 59The 60.Fn kvm_open 61function is first called to obtain a descriptor for all subsequent calls. 62.Sh COMPATIBILITY 63The kvm interface was first introduced in SunOS. 64A considerable 65number of programs have been developed that use this interface, 66making backward compatibility highly desirable. 67In most respects, the Sun kvm interface is consistent and clean. 68Accordingly, the generic portion of the interface (i.e., 69.Fn kvm_open , 70.Fn kvm_close , 71.Fn kvm_read , 72.Fn kvm_write , 73and 74.Fn kvm_nlist ) 75has been incorporated into the 76.Bx 77interface. 78Indeed, many kvm 79applications (i.e., debuggers and statistical monitors) use only 80this subset of the interface. 81.Pp 82The process interface was not kept. 83This is not a portability 84issue since any code that manipulates processes is inherently 85machine dependent. 86.Pp 87Finally, the Sun kvm error reporting semantics are poorly defined. 88The library can be configured either to print errors to 89.Dv stderr 90automatically, 91or to print no error messages at all. 92In the latter case, the nature of the error cannot be determined. 93To overcome this, the 94.Bx 95interface includes a 96routine, 97.Xr kvm_geterr 3 , 98to return (not print out) the error message 99corresponding to the most recent error condition on the 100given descriptor. 101.Sh SEE ALSO 102.Xr kvm_close 3 , 103.Xr kvm_getargv 3 , 104.Xr kvm_getenvv 3 , 105.Xr kvm_geterr 3 , 106.Xr kvm_getfiles 3 , 107.Xr kvm_getloadavg 3 , 108.Xr kvm_getprocs 3 , 109.Xr kvm_getswapinfo 3 , 110.Xr kvm_nlist 3 , 111.Xr kvm_open 3 , 112.Xr kvm_openfiles 3 , 113.Xr kvm_read 3 , 114.Xr kvm_write 3 , 115.Xr kmem 4 , 116.Xr mem 4 117