1.\" $NetBSD: kvm.3,v 1.8 2002/10/01 19:18:12 wiz 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. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by the University of 21.\" California, Berkeley and its contributors. 22.\" 4. Neither the name of the University nor the names of its contributors 23.\" may be used to endorse or promote products derived from this software 24.\" without specific prior written permission. 25.\" 26.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36.\" SUCH DAMAGE. 37.\" 38.\" @(#)kvm.3 8.1 (Berkeley) 6/4/93 39.\" 40.Dd August 18, 2002 41.Dt KVM 3 42.Os 43.Sh NAME 44.Nm kvm 45.Nd kernel memory interface 46.Sh LIBRARY 47.Lb libkvm 48.Sh DESCRIPTION 49The 50.Nm 51library provides a uniform interface for accessing kernel virtual memory 52images, including live systems and crashdumps. 53Access to live systems is via 54.Pa /dev/mem 55while crashdumps can be examined via the core file generated by 56.Xr savecore 8 . 57The interface behaves identically in both cases. 58Memory can be read and written, kernel symbol addresses can be 59looked up efficiently, and information about user processes can 60be gathered. 61.Pp 62.Fn kvm_open 63is first called to obtain a descriptor for all subsequent calls. 64.Sh COMPATIBILITY 65The kvm interface was first introduced in SunOS. 66A considerable number of programs have been developed that use this 67interface, making backward compatibility highly desirable. 68In most respects, the Sun kvm interface is consistent and clean. 69Accordingly, the generic portion of the interface (i.e., 70.Fn kvm_open , 71.Fn kvm_close , 72.Fn kvm_read , 73.Fn kvm_write , 74and 75.Fn kvm_nlist ) 76has been incorporated into the 77.Bx 78interface. 79Indeed, many kvm applications (i.e., debuggers and statistical monitors) 80use only this subset of the interface. 81.Pp 82The process interface was not kept. 83This is not a portability issue since any code that manipulates 84processes is inherently machine dependent. 85.Pp 86Finally, the Sun kvm error reporting semantics are poorly defined. 87The library can be configured either to print errors to stderr automatically, 88or to print no error messages at all. 89In the latter case, the nature of the error cannot be determined. 90To overcome this, the 91.Bx 92interface includes a routine, 93.Xr kvm_geterr 3 , 94to return (not print out) the error message corresponding to the most 95recent error condition on the given descriptor. 96.Sh FILES 97.Bl -tag -width /dev/mem -compact 98.It Pa /dev/mem 99interface to physical memory 100.El 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_getloadavg 3 , 107.Xr kvm_getprocs 3 , 108.Xr kvm_nlist 3 , 109.Xr kvm_open 3 , 110.Xr kvm_openfiles 3 , 111.Xr kvm_read 3 , 112.Xr kvm_write 3 113