1.\" $NetBSD: kvm_read.3,v 1.8 2003/08/07 16:44:39 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_read.3 8.1 (Berkeley) 6/4/93 35.\" 36.Dd June 4, 1993 37.Dt KVM_READ 3 38.Os 39.Sh NAME 40.Nm kvm_read , 41.Nm kvm_write 42.Nd read or write kernel virtual memory 43.Sh LIBRARY 44.Lb libkvm 45.Sh SYNOPSIS 46.In kvm.h 47.Ft ssize_t 48.Fn kvm_read "kvm_t *kd" "u_long addr" "void *buf" "size_t nbytes" 49.Ft ssize_t 50.Fn kvm_write "kvm_t *kd" "u_long addr" "const void *buf" "size_t nbytes" 51.Sh DESCRIPTION 52The 53.Fn kvm_read 54and 55.Fn kvm_write 56functions are used to read and write kernel virtual memory (or a crash 57dump file). 58See 59.Fn kvm_open 3 60or 61.Fn kvm_openfiles 3 62for information regarding opening kernel virtual memory and crash dumps. 63.Pp 64The 65.Fn kvm_read 66function transfers 67.Fa nbytes 68bytes of data from 69the kernel space address 70.Fa addr 71to 72.Fa buf . 73Conversely, 74.Fn kvm_write 75transfers data from 76.Fa buf 77to 78.Fa addr . 79Unlike their SunOS counterparts, these functions cannot be used to 80read or write process address spaces. 81.Sh RETURN VALUES 82Upon success, the number of bytes actually transferred is returned. 83Otherwise, -1 is returned. 84.Sh SEE ALSO 85.Xr kvm 3 , 86.Xr kvm_close 3 , 87.Xr kvm_getargv 3 , 88.Xr kvm_getenvv 3 , 89.Xr kvm_geterr 3 , 90.Xr kvm_getprocs 3 , 91.Xr kvm_nlist 3 , 92.Xr kvm_open 3 , 93.Xr kvm_openfiles 3 94