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_read.3 8.1 (Berkeley) 6/4/93 37.\" $FreeBSD$ 38.\" 39.Dd June 4, 1993 40.Dt KVM_READ 3 41.Os 42.Sh NAME 43.Nm kvm_read , 44.Nm kvm_write 45.Nd read or write kernel virtual memory 46.Sh LIBRARY 47.Lb libkvm 48.Sh SYNOPSIS 49.In kvm.h 50.Ft ssize_t 51.Fn kvm_read "kvm_t *kd" "unsigned long addr" "void *buf" "size_t nbytes" 52.Ft ssize_t 53.Fn kvm_write "kvm_t *kd" "unsigned 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). 61See 62.Fn kvm_open 3 63or 64.Fn kvm_openfiles 3 65for information regarding opening kernel virtual memory and crash dumps. 66.Pp 67The 68.Fn kvm_read 69function transfers 70.Fa nbytes 71bytes of data from 72the kernel space address 73.Fa addr 74to 75.Fa buf . 76Conversely, 77.Fn kvm_write 78transfers data from 79.Fa buf 80to 81.Fa addr . 82Unlike their SunOS counterparts, these functions cannot be used to 83read or write process address spaces. 84.Sh RETURN VALUES 85Upon success, the number of bytes actually transferred is returned. 86Otherwise, -1 is returned. 87.Sh SEE ALSO 88.Xr kvm 3 , 89.Xr kvm_close 3 , 90.Xr kvm_getargv 3 , 91.Xr kvm_getenvv 3 , 92.Xr kvm_geterr 3 , 93.Xr kvm_getprocs 3 , 94.Xr kvm_nlist 3 , 95.Xr kvm_open 3 , 96.Xr kvm_openfiles 3 97