1.\" $NetBSD: kvm.3,v 1.2 1996/03/18 22:33:11 thorpej 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 June 4, 1993 41.Dt KVM 3 42.Os 43.Sh NAME 44.Nm kvm 45.Nd kernel memory interface 46.Sh DESCRIPTION 47The 48.Xr kvm 3 49library provides a uniform interface for accessing kernel virtual memory 50images, including live systems and crashdumps. 51Access to live systems is via 52/dev/mem 53while crashdumps can be examined via the core file generated by 54.Xr savecore 8 . 55The interface behaves identically in both cases. 56Memory can be read and written, kernel symbol addresses can be 57looked up efficiently, and information about user processes can 58be gathered. 59.Pp 60.Fn kvm_open 61is first called to obtain a descriptor for all subsequent calls. 62.Sh COMPATIBILITY 63The kvm interface was first introduced in SunOS. A considerable 64number of programs have been developed that use this interface, 65making backward compatibility highly desirable. 66In most respects, the Sun kvm interface is consistent and clean. 67Accordingly, the generic portion of the interface (i.e., 68.Fn kvm_open , 69.Fn kvm_close , 70.Fn kvm_read , 71.Fn kvm_write , 72and 73.Fn kvm_nlist ) 74has been incorporated into the BSD interface. Indeed, many kvm 75applications (i.e., debuggers and statistical monitors) use only 76this subset of the interface. 77.Pp 78The process interface was not kept. This is not a portability 79issue since any code that manipulates processes is inherently 80machine 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 BSD interface includes a 87routine, 88.Xr kvm_geterr 3 , 89to return (not print out) the error message 90corresponding to the most recent error condition on the 91given descriptor. 92.Sh SEE ALSO 93.Xr kvm_close 3 , 94.Xr kvm_getargv 3 , 95.Xr kvm_getenvv 3 , 96.Xr kvm_geterr 3 , 97.Xr kvm_getloadavg 3 , 98.Xr kvm_getprocs 3 , 99.Xr kvm_nlist 3 , 100.Xr kvm_open 3 , 101.Xr kvm_openfiles 3 , 102.Xr kvm_read 3 , 103.Xr kvm_write 3 104