ia64/linux-2.6.18-xen.hg

view Documentation/device-mapper/linear.txt @ 524:7f8b544237bf

netfront: Allow netfront in domain 0.

This is useful if your physical network device is in a utility domain.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Tue Apr 15 15:18:58 2008 +0100 (2008-04-15)
parents 831230e53067
children
line source
1 dm-linear
2 =========
4 Device-Mapper's "linear" target maps a linear range of the Device-Mapper
5 device onto a linear range of another device. This is the basic building
6 block of logical volume managers.
8 Parameters: <dev path> <offset>
9 <dev path>: Full pathname to the underlying block-device, or a
10 "major:minor" device-number.
11 <offset>: Starting sector within the device.
14 Example scripts
15 ===============
16 [[
17 #!/bin/sh
18 # Create an identity mapping for a device
19 echo "0 `blockdev --getsize $1` linear $1 0" | dmsetup create identity
20 ]]
23 [[
24 #!/bin/sh
25 # Join 2 devices together
26 size1=`blockdev --getsize $1`
27 size2=`blockdev --getsize $2`
28 echo "0 $size1 linear $1 0
29 $size1 $size2 linear $2 0" | dmsetup create joined
30 ]]
33 [[
34 #!/usr/bin/perl -w
35 # Split a device into 4M chunks and then join them together in reverse order.
37 my $name = "reverse";
38 my $extent_size = 4 * 1024 * 2;
39 my $dev = $ARGV[0];
40 my $table = "";
41 my $count = 0;
43 if (!defined($dev)) {
44 die("Please specify a device.\n");
45 }
47 my $dev_size = `blockdev --getsize $dev`;
48 my $extents = int($dev_size / $extent_size) -
49 (($dev_size % $extent_size) ? 1 : 0);
51 while ($extents > 0) {
52 my $this_start = $count * $extent_size;
53 $extents--;
54 $count++;
55 my $this_offset = $extents * $extent_size;
57 $table .= "$this_start $extent_size linear $dev $this_offset\n";
58 }
60 `echo \"$table\" | dmsetup create $name`;
61 ]]