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. 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.Dd November 27, 2015 33.Dt KVM_READ 3 34.Os 35.Sh NAME 36.Nm kvm_read , 37.Nm kvm_read2 , 38.Nm kvm_write 39.Nd read or write kernel virtual memory 40.Sh LIBRARY 41.Lb libkvm 42.Sh SYNOPSIS 43.In kvm.h 44.Ft ssize_t 45.Fn kvm_read "kvm_t *kd" "unsigned long addr" "void *buf" "size_t nbytes" 46.Ft ssize_t 47.Fn kvm_read2 "kvm_t *kd" "kvaddr_t 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 , 53.Fn kvm_read2 , 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 60for information regarding opening kernel virtual memory and crash dumps. 61.Pp 62The 63.Fn kvm_read 64and 65.Fn kvm_read2 66functions transfer 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.Pp 82The 83.Fn kvm_read2 84function uses a different type 85.Pq Vt kvaddr_t 86for the 87.Fa addr 88argument to allow use of addresses larger than 89.Dv ULONG_MAX 90when examining non-native kernel images. 91.Sh RETURN VALUES 92Upon success, the number of bytes actually transferred is returned. 93Otherwise, -1 is returned. 94.Sh SEE ALSO 95.Xr kvm 3 , 96.Xr kvm_close 3 , 97.Xr kvm_getargv 3 , 98.Xr kvm_getenvv 3 , 99.Xr kvm_geterr 3 , 100.Xr kvm_getprocs 3 , 101.Xr kvm_nlist 3 , 102.Xr kvm_open 3 , 103.Xr kvm_openfiles 3 104.Sh HISTORY 105The 106.Fn kvm_read2 107function first appeared in 108.Fx 11.0 . 109