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.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)kvm_read.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD$ 34.\" 35.Dd June 4, 1993 36.Dt KVM_READ 3 37.Os 38.Sh NAME 39.Nm kvm_read , 40.Nm kvm_write 41.Nd read or write kernel virtual memory 42.Sh LIBRARY 43.Lb libkvm 44.Sh SYNOPSIS 45.In kvm.h 46.Ft ssize_t 47.Fn kvm_read "kvm_t *kd" "unsigned long addr" "void *buf" "size_t nbytes" 48.Ft ssize_t 49.Fn kvm_write "kvm_t *kd" "unsigned long addr" "const void *buf" "size_t nbytes" 50.Sh DESCRIPTION 51The 52.Fn kvm_read 53and 54.Fn kvm_write 55functions are used to read and write kernel virtual memory (or a crash 56dump file). 57See 58.Fn kvm_open 3 59or 60.Fn kvm_openfiles 3 61for information regarding opening kernel virtual memory and crash dumps. 62.Pp 63The 64.Fn kvm_read 65function transfers 66.Fa nbytes 67bytes of data from 68the kernel space address 69.Fa addr 70to 71.Fa buf . 72Conversely, 73.Fn kvm_write 74transfers data from 75.Fa buf 76to 77.Fa addr . 78Unlike their SunOS counterparts, these functions cannot be used to 79read or write process address spaces. 80.Sh RETURN VALUES 81Upon success, the number of bytes actually transferred is returned. 82Otherwise, -1 is returned. 83.Sh SEE ALSO 84.Xr kvm 3 , 85.Xr kvm_close 3 , 86.Xr kvm_getargv 3 , 87.Xr kvm_getenvv 3 , 88.Xr kvm_geterr 3 , 89.Xr kvm_getprocs 3 , 90.Xr kvm_nlist 3 , 91.Xr kvm_open 3 , 92.Xr kvm_openfiles 3 93