0cd475f86b
Document that the 7f911abe "Add support to libkvm for reading vmcores
from other architectures." added functions appeared first in FreeBSD 11.0.
112 lines
3.3 KiB
Groff
112 lines
3.3 KiB
Groff
.\" Copyright (c) 1992, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software developed by the Computer Systems
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.\" Engineering group at Lawrence Berkeley Laboratory under DARPA contract
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.\" BG 91-66 and contributed to Berkeley.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)kvm_read.3 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd November 27, 2015
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.Dt KVM_READ 3
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.Os
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.Sh NAME
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.Nm kvm_read ,
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.Nm kvm_read2 ,
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.Nm kvm_write
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.Nd read or write kernel virtual memory
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.Sh LIBRARY
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.Lb libkvm
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.Sh SYNOPSIS
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.In kvm.h
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.Ft ssize_t
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.Fn kvm_read "kvm_t *kd" "unsigned long addr" "void *buf" "size_t nbytes"
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.Ft ssize_t
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.Fn kvm_read2 "kvm_t *kd" "kvaddr_t addr" "void *buf" "size_t nbytes"
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.Ft ssize_t
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.Fn kvm_write "kvm_t *kd" "unsigned long addr" "const void *buf" "size_t nbytes"
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.Sh DESCRIPTION
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The
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.Fn kvm_read ,
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.Fn kvm_read2 ,
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and
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.Fn kvm_write
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functions are used to read and write kernel virtual memory (or a crash
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dump file).
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See
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.Fn kvm_open 3
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for information regarding opening kernel virtual memory and crash dumps.
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.Pp
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The
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.Fn kvm_read
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and
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.Fn kvm_read2
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functions transfer
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.Fa nbytes
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bytes of data from
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the kernel space address
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.Fa addr
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to
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.Fa buf .
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Conversely,
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.Fn kvm_write
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transfers data from
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.Fa buf
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to
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.Fa addr .
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Unlike their SunOS counterparts, these functions cannot be used to
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read or write process address spaces.
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.Pp
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The
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.Fn kvm_read2
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function uses a different type
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.Pq Vt kvaddr_t
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for the
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.Fa addr
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argument to allow use of addresses larger than
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.Dv ULONG_MAX
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when examining non-native kernel images.
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.Sh RETURN VALUES
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Upon success, the number of bytes actually transferred is returned.
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Otherwise, -1 is returned.
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.Sh SEE ALSO
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.Xr kvm 3 ,
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.Xr kvm_close 3 ,
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.Xr kvm_getargv 3 ,
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.Xr kvm_getenvv 3 ,
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.Xr kvm_geterr 3 ,
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.Xr kvm_getprocs 3 ,
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.Xr kvm_nlist 3 ,
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.Xr kvm_open 3 ,
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.Xr kvm_openfiles 3
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.Sh HISTORY
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The
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.Fn kvm_read2
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function first appeared in
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.Fx 11.0 .
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