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.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" @(#)kvm.3 8.1 (Berkeley) 6/4/93 37.\" $FreeBSD: src/lib/libkvm/kvm.3,v 1.7.2.2 2001/08/17 15:43:04 ru Exp $ 38.\" 39.Dd June 4, 1993 40.Dt KVM 3 41.Os 42.Sh NAME 43.Nm kvm 44.Nd kernel memory interface 45.Sh LIBRARY 46.Lb libkvm 47.Sh DESCRIPTION 48The 49.Xr kvm 3 50library provides a uniform interface for accessing kernel virtual memory 51images, including live systems and crash dumps. 52Access to live systems is via 53.Pa /dev/mem 54while crash dumps can be examined via the core file generated by 55.Xr savecore 8 . 56The interface behaves identically in both cases. 57Memory can be read and written, kernel symbol addresses can be 58looked up efficiently, and information about user processes can 59be gathered. 60.Pp 61.Fn kvm_open 62is first called to obtain a descriptor for all subsequent calls. 63.Sh COMPATIBILITY 64The kvm interface was first introduced in SunOS. A 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. Indeed, many kvm 78applications (i.e., debuggers and statistical monitors) use only 79this subset of the interface. 80.Pp 81The process interface was not kept. This is not a portability 82issue since any code that manipulates processes is inherently 83machine dependent. 84.Pp 85Finally, the Sun kvm error reporting semantics are poorly defined. 86The library can be configured either to print errors to stderr automatically, 87or to print no error messages at all. 88In the latter case, the nature of the error cannot be determined. 89To overcome this, the 90.Bx 91interface includes a 92routine, 93.Xr kvm_geterr 3 , 94to return (not print out) the error message 95corresponding to the most recent error condition on the 96given descriptor. 97.Sh SEE ALSO 98.Xr kvm_close 3 , 99.Xr kvm_getargv 3 , 100.Xr kvm_getenvv 3 , 101.Xr kvm_geterr 3 , 102.Xr kvm_getfiles 3 , 103.Xr kvm_getloadavg 3 , 104.Xr kvm_getprocs 3 , 105.Xr kvm_getswapinfo 3 , 106.Xr kvm_nlist 3 , 107.Xr kvm_open 3 , 108.Xr kvm_openfiles 3 , 109.Xr kvm_read 3 , 110.Xr kvm_write 3 111