1.\" $NetBSD: kvm_read.3,v 1.6 2002/10/01 19:18:13 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_read.3 8.1 (Berkeley) 6/4/93 39.\" 40.Dd June 4, 1993 41.Dt KVM_READ 3 42.Os 43.Sh NAME 44.Nm kvm_read , 45.Nm kvm_write 46.Nd read or write kernel virtual memory 47.Sh LIBRARY 48.Lb libkvm 49.Sh SYNOPSIS 50.Fd #include \*[Lt]kvm.h\*[Gt] 51.Ft ssize_t 52.Fn kvm_read "kvm_t *kd" "u_long addr" "void *buf" "size_t nbytes" 53.Ft ssize_t 54.Fn kvm_write "kvm_t *kd" "u_long addr" "const void *buf" "size_t nbytes" 55.Sh DESCRIPTION 56The 57.Fn kvm_read 58and 59.Fn kvm_write 60functions are used to read and write kernel virtual memory (or a crash 61dump file). 62See 63.Fn kvm_open 3 64or 65.Fn kvm_openfiles 3 66for information regarding opening kernel virtual memory and crash dumps. 67.Pp 68The 69.Fn kvm_read 70function transfers 71.Fa nbytes 72bytes of data from 73the kernel space address 74.Fa addr 75to 76.Fa buf . 77Conversely, 78.Fn kvm_write 79transfers data from 80.Fa buf 81to 82.Fa addr . 83Unlike their SunOS counterparts, these functions cannot be used to 84read or write process address spaces. 85.Sh RETURN VALUES 86Upon success, the number of bytes actually transferred is returned. 87Otherwise, -1 is returned. 88.Sh SEE ALSO 89.Xr kvm 3 , 90.Xr kvm_close 3 , 91.Xr kvm_getargv 3 , 92.Xr kvm_getenvv 3 , 93.Xr kvm_geterr 3 , 94.Xr kvm_getprocs 3 , 95.Xr kvm_nlist 3 , 96.Xr kvm_open 3 , 97.Xr kvm_openfiles 3 98