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. 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: src/lib/libkvm/kvm.3,v 1.7.2.2 2001/08/17 15:43:04 ru Exp $ 34.\" 35.Dd June 4, 1993 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.Xr kvm 3 46library provides a uniform interface for accessing kernel virtual memory 47images, including live systems and crash dumps. 48Access to live systems is via 49.Pa /dev/mem 50while crash dumps can be examined via the core file generated by 51.Xr savecore 8 . 52The interface behaves identically in both cases. 53Memory can be read and written, kernel symbol addresses can be 54looked up efficiently, and information about user processes can 55be gathered. 56.Pp 57.Fn kvm_open 58is first called to obtain a descriptor for all subsequent calls. 59.Sh COMPATIBILITY 60The kvm interface was first introduced in SunOS. A considerable 61number of programs have been developed that use this interface, 62making backward compatibility highly desirable. 63In most respects, the Sun kvm interface is consistent and clean. 64Accordingly, the generic portion of the interface (i.e., 65.Fn kvm_open , 66.Fn kvm_close , 67.Fn kvm_read , 68.Fn kvm_write , 69and 70.Fn kvm_nlist ) 71has been incorporated into the 72.Bx 73interface. Indeed, many kvm 74applications (i.e., debuggers and statistical monitors) use only 75this subset of the interface. 76.Pp 77The process interface was not kept. This is not a portability 78issue since any code that manipulates processes is inherently 79machine dependent. 80.Pp 81Finally, the Sun kvm error reporting semantics are poorly defined. 82The library can be configured either to print errors to stderr automatically, 83or to print no error messages at all. 84In the latter case, the nature of the error cannot be determined. 85To overcome this, the 86.Bx 87interface includes a 88routine, 89.Xr kvm_geterr 3 , 90to return (not print out) the error message 91corresponding to the most recent error condition on the 92given descriptor. 93.Sh SEE ALSO 94.Xr kinfo 3 , 95.Xr kvm_close 3 , 96.Xr kvm_getargv 3 , 97.Xr kvm_getenvv 3 , 98.Xr kvm_geterr 3 , 99.Xr kvm_getfiles 3 , 100.Xr kvm_getloadavg 3 , 101.Xr kvm_getprocs 3 , 102.Xr kvm_getswapinfo 3 , 103.Xr kvm_nlist 3 , 104.Xr kvm_open 3 , 105.Xr kvm_openfiles 3 , 106.Xr kvm_read 3 , 107.Xr kvm_write 3 108