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.\" $FreeBSD$ 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 DESCRIPTION 46The 47.Xr kvm 3 48library provides a uniform interface for accessing kernel virtual memory 49images, including live systems and crash dumps. 50Access to live systems is via 51/dev/mem 52while crash dumps can be examined via the core file generated by 53.Xr savecore 8 . 54The interface behaves identically in both cases. 55Memory can be read and written, kernel symbol addresses can be 56looked up efficiently, and information about user processes can 57be gathered. 58.Pp 59.Fn kvm_open 60is first called to obtain a descriptor for all subsequent calls. 61.Sh COMPATIBILITY 62The kvm interface was first introduced in SunOS. A considerable 63number of programs have been developed that use this interface, 64making backward compatibility highly desirable. 65In most respects, the Sun kvm interface is consistent and clean. 66Accordingly, the generic portion of the interface (i.e., 67.Fn kvm_open , 68.Fn kvm_close , 69.Fn kvm_read , 70.Fn kvm_write , 71and 72.Fn kvm_nlist ) 73has been incorporated into the BSD interface. 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 BSD interface includes a 86routine, 87.Xr kvm_geterr 3 , 88to return (not print out) the error message 89corresponding to the most recent error condition on the 90given descriptor. 91.Sh SEE ALSO 92.Xr kvm_close 3 , 93.Xr kvm_getargv 3 , 94.Xr kvm_getenvv 3 , 95.Xr kvm_geterr 3 , 96.Xr kvm_getfiles 3 , 97.Xr kvm_getloadavg 3 , 98.Xr kvm_getprocs 3 , 99.Xr kvm_getswapinfo 3 , 100.Xr kvm_nlist 3 , 101.Xr kvm_open 3 , 102.Xr kvm_openfiles 3 , 103.Xr kvm_read 3 , 104.Xr kvm_write 3 105