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-rw-r--r--documentation/ref-manual/ref-variables.xml35
1 files changed, 27 insertions, 8 deletions
diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index 7219fe6d2f..7a8ca3b94e 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -1620,26 +1620,45 @@
1620 <glossentry id='var-DISK_SIGNATURE'><glossterm>DISK_SIGNATURE</glossterm> 1620 <glossentry id='var-DISK_SIGNATURE'><glossterm>DISK_SIGNATURE</glossterm>
1621 <glossdef> 1621 <glossdef>
1622 <para> 1622 <para>
1623 Automatically generated random signature that allows the 1623 A 32-bit MBR disk signature used by
1624 OpenEmbedded build system to create a boot 1624 <filename>directdisk</filename> images.
1625 loader configuration.
1626 <filename>DISK_SIGNATURE</filename> is different each time
1627 a <filename>directdisk</filename> image is built.
1628 <note> 1625 <note>
1629 The "live" option used with 1626 The "live" option used with
1630 <link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link> 1627 <link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link>
1631 produces an image file that can be copied directly to 1628 produces an image file that can be copied directly to
1632 a CD or USB device and run as is. 1629 a CD or USB device and run as is.
1633 </note> 1630 </note>
1634 The auto-generated <filename>DISK_SIGNATURE</filename> sets 1631 By default, the signature is set to an automatically
1635 <filename>SYSLINUX_ROOT</filename> as follows: 1632 generated random value that allows the OpenEmbedded
1633 build system to create a boot loader.
1634 You can override the signature in the image recipe
1635 by setting <filename>DISK_SIGNATURE</filename> to an
1636 8-digit hex string.
1637 You might want to override
1638 <filename>DISK_SIGNATURE</filename> if you want the disk
1639 signature to remain constant between image builds.
1640 </para>
1641
1642 <para>
1643 When using Linux 3.8 or later, you can use
1644 <filename>DISK_SIGNATURE</filename> to specify the root
1645 by UUID to allow the kernel to locate the root device
1646 even if the device name changes due to differences in
1647 hardware configuration.
1648 By default, <filename>SYSLINUX_ROOT</filename> is set
1649 as follows:
1650 <literallayout class='monospaced'>
1651 SYSLINUX_ROOT = "root=/dev/sda2"
1652 </literallayout>
1653 However, you can change this to locate the root device
1654 using the disk signature instead:
1636 <literallayout class='monospaced'> 1655 <literallayout class='monospaced'>
1637 SYSLINUX_ROOT = "root=PARTUUID=${DISK_SIGNATURE}-02" 1656 SYSLINUX_ROOT = "root=PARTUUID=${DISK_SIGNATURE}-02"
1638 </literallayout> 1657 </literallayout>
1639 </para> 1658 </para>
1640 1659
1641 <para> 1660 <para>
1642 It is possible to set the 1661 As previously mentioned, it is possible to set the
1643 <filename>DISK_SIGNATURE</filename> variable in your 1662 <filename>DISK_SIGNATURE</filename> variable in your
1644 <filename>local.conf</filename> file to a fixed 1663 <filename>local.conf</filename> file to a fixed
1645 value if you do not want <filename>syslinux.cfg</filename> 1664 value if you do not want <filename>syslinux.cfg</filename>