410 lines
6.6 KiB
HTML
410 lines
6.6 KiB
HTML
<HTML
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><HEAD
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><TITLE
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>Configure the boot loader</TITLE
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><META
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NAME="GENERATOR"
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TITLE="Configure the LILO boot
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>Remote Serial Console HOWTO</TH
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><DIV
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CLASS="CHAPTER"
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><H1
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><A
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NAME="CONFIGURE-BOOT-LOADER"
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></A
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>Chapter 4. Configure the boot loader</H1
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><DIV
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CLASS="TOC"
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><DL
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><DT
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><B
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>Table of Contents</B
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></DT
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><DT
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>4.1. <A
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HREF="configure-boot-loader-lilo.html"
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>Configure the <SPAN
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CLASS="APPLICATION"
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>LILO</SPAN
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> boot
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loader</A
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></DT
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><DT
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>4.2. <A
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HREF="configure-boot-loader-grub.html"
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>Configure the <SPAN
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CLASS="APPLICATION"
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>GRUB</SPAN
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> boot
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loader</A
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></DT
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><DT
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>4.3. <A
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HREF="configure-boot-loader-syslinux.html"
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>Configure the <SPAN
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CLASS="APPLICATION"
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>SYSLINUX</SPAN
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> boot
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loader</A
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></DT
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></DL
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></DIV
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><P
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>When a PC boots the CPU it runs code from Read-Only Memory.
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This code is the Basic Input/Output System, or
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<SPAN
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CLASS="ACRONYM"
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>BIOS</SPAN
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>. The <SPAN
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CLASS="ACRONYM"
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>BIOS</SPAN
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> then loads a
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boot loader from the Master Boot Record of the first hard
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disk.<A
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NAME="AEN810"
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HREF="#FTN.AEN810"
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><SPAN
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CLASS="footnote"
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>[1]</SPAN
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></A
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>
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In turn, the boot loader reads the operating system into memory and
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then runs it.<A
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NAME="AEN822"
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HREF="#FTN.AEN822"
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><SPAN
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CLASS="footnote"
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>[2]</SPAN
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></A
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></P
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><P
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>Neither the <SPAN
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CLASS="ACRONYM"
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>BIOS</SPAN
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> nor the boot loader are
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strictly necessary. For example, there are <A
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HREF="http://www.acl.lanl.gov/linuxbios/"
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TARGET="_top"
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>versions of Linux</A
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>
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that run directly from the flash memory which usually contains the
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<SPAN
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CLASS="ACRONYM"
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>BIOS</SPAN
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>. Linux was originally designed to run
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without an interactive boot loader, by placing the kernel at
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particular sectors of the disk.</P
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><P
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>The benefits of using a boot loader are:</P
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><P
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></P
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><UL
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><LI
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><P
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>Multiple operating systems can be booted. See the <A
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HREF="http://www.tldp.org/HOWTO/Linux+Windows-HOWTO/"
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TARGET="_top"
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><I
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CLASS="CITETITLE"
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><SPAN
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CLASS="SYSTEMITEM"
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>Linux</SPAN
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> + <SPAN
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CLASS="SYSTEMITEM"
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>Windows</SPAN
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> HOWTO</I
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></A
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> for
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more information.</P
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></LI
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><LI
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><P
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>Parameters can be passed to the kernel interactively. This
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is useful for solving hardware problems; for example, some
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interrupt lines can be disabled, direct memory access to some
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drives can be disabled, and so on. See the <A
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HREF="http://www.tldp.org/HOWTO/BootPrompt-HOWTO.html"
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TARGET="_top"
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><I
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CLASS="CITETITLE"
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><SPAN
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CLASS="SYSTEMITEM"
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>Linux</SPAN
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>
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BootPrompt-HOWTO</I
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></A
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> for a list of kernel
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parameters.</P
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></LI
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><LI
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><P
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>Differing kernels can be interactively loaded. This is
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useful when deploying a new kernel, as it provides simple fallback
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to a proven kernel.</P
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></LI
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></UL
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><P
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>For these reasons systems administrators want to be able to
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interactively control the boot loader from the serial
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console.</P
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><P
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><SPAN
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CLASS="APPLICATION"
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>LILO</SPAN
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>,
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<SPAN
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CLASS="APPLICATION"
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>GRUB</SPAN
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> and
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<SPAN
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CLASS="APPLICATION"
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>SYSLINUX</SPAN
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> are popular boot loaders for
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<SPAN
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CLASS="PRODUCTNAME"
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><SPAN
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CLASS="ACRONYM"
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>IBM</SPAN
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>
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<SPAN
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CLASS="ACRONYM"
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>PC</SPAN
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>s</SPAN
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>. Find which of these boot
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loaders your <SPAN
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CLASS="SYSTEMITEM"
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>Linux</SPAN
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>
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installation uses and then follow the instructions for your boot
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loader in the following section.</P
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></DIV
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><H3
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CLASS="FOOTNOTES"
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>Notes</H3
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><TABLE
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BORDER="0"
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CLASS="FOOTNOTES"
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WIDTH="100%"
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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WIDTH="5%"
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><A
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NAME="FTN.AEN810"
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HREF="configure-boot-loader.html#AEN810"
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><SPAN
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CLASS="footnote"
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>[1]</SPAN
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></A
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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WIDTH="95%"
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><P
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>As usual with <SPAN
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CLASS="PRODUCTNAME"
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><SPAN
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CLASS="ACRONYM"
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>IBM
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PC/AT</SPAN
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></SPAN
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> hardware <SPAN
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CLASS="QUOTE"
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>"loads a boot loader
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from the <SPAN
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CLASS="ACRONYM"
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>MBR</SPAN
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> of the first hard disk"</SPAN
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> is a
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simplification. <SPAN
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CLASS="ACRONYM"
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>BIOS</SPAN
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> settings permitting, the
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<SPAN
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CLASS="ACRONYM"
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>MBR</SPAN
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> can be loaded from the first two detected
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hard disks of any controller card containing a
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<SPAN
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CLASS="ACRONYM"
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>BIOS</SPAN
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> extension. Thus the
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<SPAN
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CLASS="ACRONYM"
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>MBR</SPAN
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> can be loaded from one of the first two
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detected <SPAN
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CLASS="ACRONYM"
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>IDE</SPAN
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> disks and one of the first two
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detected <SPAN
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CLASS="ACRONYM"
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>SCSI</SPAN
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> disks.</P
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></TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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WIDTH="5%"
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><A
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NAME="FTN.AEN822"
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HREF="configure-boot-loader.html#AEN822"
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><SPAN
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CLASS="footnote"
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>[2]</SPAN
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></A
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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WIDTH="95%"
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><P
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>Another simplification. A 512 byte <SPAN
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CLASS="ACRONYM"
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>MBR</SPAN
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>
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is too small to contain a program big enough to load a complex
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operating system. Thus most boot loaders have two stages, the
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first stage is located in the <SPAN
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CLASS="ACRONYM"
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>MBR</SPAN
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> and is only
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able to load the second stage of the boot loader from somewhere on
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a disk (such as the boot sector of the first partition). The
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second stage of the boot loader presents the user interface and
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loads the operating system.</P
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></TD
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></TR
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></TABLE
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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SUMMARY="Footer navigation table"
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WIDTH="33%"
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HREF="bios.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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VALIGN="top"
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HREF="index.html"
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>Home</A
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>Next</A
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><TR
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><TD
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WIDTH="33%"
|
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ALIGN="left"
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VALIGN="top"
|
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>Optionally configure the <SPAN
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CLASS="ACRONYM"
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>BIOS</SPAN
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></TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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> </TD
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><TD
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WIDTH="33%"
|
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ALIGN="right"
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VALIGN="top"
|
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>Configure the <SPAN
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CLASS="APPLICATION"
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>LILO</SPAN
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> boot
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loader</TD
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></TR
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></TABLE
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