1.\" $NetBSD: kvm.3,v 1.11 2003/08/07 16:44:35 agc Exp $ 2.\" 3.\" Copyright (c) 1992, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software developed by the Computer Systems 7.\" Engineering group at Lawrence Berkeley Laboratory under DARPA contract 8.\" BG 91-66 and contributed to Berkeley. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)kvm.3 8.1 (Berkeley) 6/4/93 35.\" 36.Dd August 18, 2002 37.Dt KVM 3 38.Os 39.Sh NAME 40.Nm kvm 41.Nd kernel memory interface 42.Sh LIBRARY 43.Lb libkvm 44.Sh DESCRIPTION 45The 46.Nm 47library provides a uniform interface for accessing kernel virtual memory 48images, including live systems and crash dumps. 49Access to live systems is via 50.Pa /dev/mem 51while crash dumps can be examined via the core file generated by 52.Xr savecore 8 . 53The interface behaves identically in both cases. 54Memory can be read and written, kernel symbol addresses can be 55looked up efficiently, and information about user processes can 56be gathered. 57.Pp 58.Fn kvm_open 59is first called to obtain a descriptor for all subsequent calls. 60.Sh COMPATIBILITY 61The kvm interface was first introduced in SunOS. 62A considerable number of programs have been developed that use this 63interface, making backward compatibility highly desirable. 64In most respects, the Sun kvm interface is consistent and clean. 65Accordingly, the generic portion of the interface (i.e., 66.Fn kvm_open , 67.Fn kvm_close , 68.Fn kvm_read , 69.Fn kvm_write , 70and 71.Fn kvm_nlist ) 72has been incorporated into the 73.Bx 74interface. 75Indeed, many kvm applications (i.e., debuggers and statistical monitors) 76use only this subset of the interface. 77.Pp 78The process interface was not kept. 79This is not a portability issue since any code that manipulates 80processes is inherently machine dependent. 81.Pp 82Finally, the Sun kvm error reporting semantics are poorly defined. 83The library can be configured either to print errors to stderr automatically, 84or to print no error messages at all. 85In the latter case, the nature of the error cannot be determined. 86To overcome this, the 87.Bx 88interface includes a routine, 89.Xr kvm_geterr 3 , 90to return (not print out) the error message corresponding to the most 91recent error condition on the given descriptor. 92.Sh FILES 93.Bl -tag -width /dev/mem -compact 94.It Pa /dev/mem 95interface to physical memory 96.El 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_getloadavg 3 , 103.Xr kvm_getlwps 3 , 104.Xr kvm_getprocs 3 , 105.Xr kvm_nlist 3 , 106.Xr kvm_open 3 , 107.Xr kvm_openfiles 3 , 108.Xr kvm_read 3 , 109.Xr kvm_write 3 110