1.\" $OpenBSD: kvm_read.3,v 1.2 1996/05/05 14:57:47 deraadt Exp $ 2.\" $NetBSD: kvm_read.3,v 1.2 1996/03/18 22:34:01 thorpej Exp $ 3.\" 4.\" Copyright (c) 1992, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" This code is derived from software developed by the Computer Systems 8.\" Engineering group at Lawrence Berkeley Laboratory under DARPA contract 9.\" BG 91-66 and contributed to Berkeley. 10.\" 11.\" Redistribution and use in source and binary forms, with or without 12.\" modification, are permitted provided that the following conditions 13.\" are met: 14.\" 1. Redistributions of source code must retain the above copyright 15.\" notice, this list of conditions and the following disclaimer. 16.\" 2. Redistributions in binary form must reproduce the above copyright 17.\" notice, this list of conditions and the following disclaimer in the 18.\" documentation and/or other materials provided with the distribution. 19.\" 3. All advertising materials mentioning features or use of this software 20.\" must display the following acknowledgement: 21.\" This product includes software developed by the University of 22.\" California, Berkeley and its contributors. 23.\" 4. Neither the name of the University nor the names of its contributors 24.\" may be used to endorse or promote products derived from this software 25.\" without specific prior written permission. 26.\" 27.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37.\" SUCH DAMAGE. 38.\" 39.\" @(#)kvm_read.3 8.1 (Berkeley) 6/4/93 40.\" 41.Dd June 4, 1993 42.Dt KVM_READ 3 43.Os 44.Sh NAME 45.Nm kvm_read , 46.Nm kvm_write 47.Nd read or write kernel virtual memory 48.Sh SYNOPSIS 49.Fd #include <kvm.h> 50.Ft ssize_t 51.Fn kvm_read "kvm_t *kd" "u_long addr" "void *buf" "size_t nbytes" 52.Ft ssize_t 53.Fn kvm_write "kvm_t *kd" "u_long addr" "const void *buf" "size_t nbytes" 54.Sh DESCRIPTION 55The 56.Fn kvm_read 57and 58.Fn kvm_write 59functions are used to read and write kernel virtual memory (or a crash 60dump file). See 61.Fn kvm_open 3 62or 63.Fn kvm_openfiles 3 64for information regarding opening kernel virtual memory and crash dumps. 65.Pp 66The 67.Fn kvm_read 68function transfers 69.Fa nbytes 70bytes of data from 71the kernel space address 72.Fa addr 73to 74.Fa buf . 75Conversely, 76.Fn kvm_write 77transfers data from 78.Fa buf 79to 80.Fa addr . 81Unlike their SunOS counterparts, these functions cannot be used to 82read or write process address spaces. 83.Sh RETURN VALUES 84Upon success, the number of bytes actually transferred is returned. 85Otherwise, -1 is returned. 86.Sh SEE ALSO 87.Xr kvm 3 , 88.Xr kvm_close 3 , 89.Xr kvm_getargv 3 , 90.Xr kvm_getenvv 3 , 91.Xr kvm_geterr 3 , 92.Xr kvm_getprocs 3 , 93.Xr kvm_nlist 3 , 94.Xr kvm_open 3 , 95.Xr kvm_openfiles 3 96