.\" $OpenBSD: kvm_read.3,v 1.7 2007/05/31 19:19:35 jmc Exp $ .\" $NetBSD: kvm_read.3,v 1.2 1996/03/18 22:34:01 thorpej Exp $ .\" .\" Copyright (c) 1992, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" This code is derived from software developed by the Computer Systems .\" Engineering group at Lawrence Berkeley Laboratory under DARPA contract .\" BG 91-66 and contributed to Berkeley. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)kvm_read.3 8.1 (Berkeley) 6/4/93 .\" .Dd $Mdocdate: May 31 2007 $ .Dt KVM_READ 3 .Os .Sh NAME .Nm kvm_read , .Nm kvm_write .Nd read or write kernel virtual memory .Sh SYNOPSIS .Fd #include <kvm.h> .Ft ssize_t .Fn kvm_read "kvm_t *kd" "u_long addr" "void *buf" "size_t nbytes" .Ft ssize_t .Fn kvm_write "kvm_t *kd" "u_long addr" "const void *buf" "size_t nbytes" .Sh DESCRIPTION The .Fn kvm_read and .Fn kvm_write functions are used to read and write kernel virtual memory (or a crash dump file). See .Fn kvm_open 3 or .Fn kvm_openfiles 3 for information regarding opening kernel virtual memory and crash dumps. .Pp The .Fn kvm_read function transfers .Fa nbytes bytes of data from the kernel space address .Fa addr to .Fa buf . Conversely, .Fn kvm_write transfers data from .Fa buf to .Fa addr . Unlike their SunOS counterparts, these functions cannot be used to read or write process address spaces. .Sh RETURN VALUES Upon successful completion, the number of bytes actually transferred is returned. Otherwise, \-1 is returned. .Sh SEE ALSO .Xr kvm 3 , .Xr kvm_close 3 , .Xr kvm_getargv 3 , .Xr kvm_getenvv 3 , .Xr kvm_geterr 3 , .Xr kvm_getprocs 3 , .Xr kvm_nlist 3 , .Xr kvm_open 3 , .Xr kvm_openfiles 3