path: root/en/preparing/bios-setup/i386.xml

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  <sect2 arch="x86" id="bios-setup"><title>Invoking the BIOS Set-Up Menu</title>

<para>

BIOS provides the basic functions needed to boot your machine to allow
your operating system to access your hardware.  Your system probably
provides a BIOS set-up menu, which is used to configure the BIOS.
Before installing, you <emphasis>must</emphasis> ensure that your BIOS
is setup correctly; not doing so can lead to intermittent crashes or
an inability to install Debian.

</para><para>

The rest of this section is lifted from the
<ulink url="&url-pc-hw-faq;"></ulink>, answering the question, <quote>How do I
enter the CMOS configuration menu?</quote>.  How you access the BIOS (or
<quote>CMOS</quote>) configuration menu depends on who wrote your BIOS
software:

</para>

<!-- From: burnesa@cat.com (Shaun Burnet) -->
<variablelist>

<varlistentry>
 <term>AMI BIOS</term>
 <listitem><para>

<keycap>Delete</keycap> key during the POST (power on self test)

</para></listitem>
</varlistentry>

<varlistentry>
 <term>Award BIOS</term>
 <listitem><para>

<keycombo>
  <keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>Esc</keycap>
</keycombo>, or <keycap>Delete</keycap> key during the POST

</para></listitem>
</varlistentry>

<varlistentry><term>DTK BIOS</term>
 <listitem><para>

<keycap>Esc</keycap> key during the POST

</para></listitem>
</varlistentry>

<varlistentry><term>IBM PS/2 BIOS</term>
 <listitem><para>

<keycombo>
  <keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>Insert</keycap>
</keycombo>
after
<keycombo>
  <keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>Delete</keycap>
</keycombo>

</para></listitem>
</varlistentry>

<varlistentry>
 <term>Phoenix BIOS</term>
 <listitem><para>

<keycombo>
  <keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>Esc</keycap>
</keycombo>
or
<keycombo>
  <keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>S</keycap>
</keycombo>
or
<keycap>F1</keycap>

</para></listitem>
</varlistentry>
</variablelist>

<para>

Information on invoking other BIOS routines can be found in
<ulink url="&url-invoking-bios-info;"></ulink>.

</para><para>

Some &arch-title; machines don't have a CMOS configuration menu in the
BIOS.  They require a software CMOS setup program.  If you don't have
the Installation and/or Diagnostics diskette for your machine, you can
try using a shareware/freeware program.  Try looking in
<ulink url="&url-simtel;"></ulink>.

</para>
  </sect2>

  <sect2 arch="x86" id="boot-dev-select"><title>Boot Device Selection</title>

<para>

Many BIOS set-up menus allow you to select the devices that will be
used to bootstrap the system. Set this to look for a bootable
operating system on <filename>A:</filename> (the first floppy disk),
then optionally the first CD-ROM device (possibly appearing as
<filename>D:</filename> or <filename>E:</filename>), and then from
<filename>C:</filename> (the first hard disk).  This setting enables
you to boot from either a floppy disk or a CD-ROM, which are the two
most common boot devices used to install Debian.

</para><para>

If you have a newer SCSI controller and you have a CD-ROM device
attached to it, you are usually able to boot from the CD-ROM.  All you
have to do is enable booting from a CD-ROM in the SCSI-BIOS of your
controller.

</para><para>

Another popular option is to boot from a USB storage device (also called
a USB memory stick or USB key). Some BIOSes can boot directly from a USB
storage device, but some cannot. You may need to configure your BIOS to boot
from a <quote>Removable drive</quote> or even from <quote>USB-ZIP</quote> to
get it to boot from the USB device.

</para><para>

Here are some details about how to set the boot order. Remember to
reset the boot order after Linux is installed, so that you restart
your machine from the hard drive.

</para>

   <sect3 id="ctbooi">
   <title>Changing the Boot Order on IDE Computers</title>

<orderedlist>
<listitem><para>

As your computer starts, press the keys to enter the BIOS
utility. Often, it is the <keycap>Delete</keycap> key. However,
consult the hardware documentation for the exact keystrokes.

</para></listitem>
<listitem><para>

Find the boot sequence in the setup utility. Its location depends on
your BIOS, but you are looking for a field that lists drives.

</para><para>


Common entries on IDE machines are C, A, cdrom or A, C, cdrom.

</para><para>


C is the hard drive, and A is the floppy drive.

</para></listitem>
<listitem><para>

Change the boot sequence setting so that the CD-ROM or the
floppy is first. Usually, the <keycap>Page Up</keycap> or
<keycap>Page Down</keycap> keys cycle
through the possible choices.

</para></listitem>
<listitem><para>

Save your changes. Instructions on the screen tell you how to
save the changes on your computer.

</para></listitem>
</orderedlist>
   </sect3>

   <sect3 id="ctboos">
   <title>Changing the Boot Order on SCSI Computers</title>
<para>

<orderedlist>
<listitem><para>

As your computer starts, press the keys to enter the SCSI setup
utility.

</para><para>

You can start the SCSI setup utility after the memory check and
the message about how to start the BIOS utility displays when you
start your computer.

</para><para>

The keystrokes you need depend on the utility. Often, it is
<keycombo><keycap>Ctrl</keycap><keycap>F2</keycap></keycombo>.
However, consult your hardware documentation for the
exact keystrokes.

</para></listitem>
<listitem><para>

Find the utility for changing the boot order.

</para></listitem>
<listitem><para>

Set the utility so that the SCSI ID of the CD drive is first on
the list.

</para></listitem>
<listitem><para>

Save your changes. Instructions on the screen tell you how to
save the changes on your computer. Often, you must press
<keycap>F10</keycap>.

</para></listitem>
</orderedlist>

</para>
   </sect3>
  </sect2>

  <sect2 arch="x86">
  <title>Miscellaneous BIOS Settings</title>

   <sect3 id="cd-settings"><title>CD-ROM Settings</title>
<para>

Some BIOS systems (such as Award BIOS) allow you to automatically set
the CD speed.  You should avoid that, and instead set it to, say, the
lowest speed.  If you get <userinput>seek failed</userinput> error
messages, this may be your problem.

</para>
   </sect3>

   <sect3><title>Extended vs. Expanded Memory</title>
<para>

If your system provides both ex<emphasis>ten</emphasis>ded and
ex<emphasis>pan</emphasis>ded memory, set it so that there is as much
extended and as little expanded memory as possible. Linux requires
extended memory and cannot use expanded memory.

</para>
   </sect3>

   <sect3><title>Virus Protection</title>
<para>

Disable any virus-warning features your BIOS may provide. If you have
a virus-protection board or other special hardware, make sure it is
disabled or physically removed while running GNU/Linux. These aren't
compatible with GNU/Linux; moreover, due to the file system
permissions and protected memory of the Linux kernel, viruses are
almost unheard of<footnote>
<para>

After installation you can enable Boot Sector protection if you
want. This offers no additional security in Linux but if you also run
Windows it may prevent a catastrophe. There is no need to tamper with
the Master Boot Record (MBR) after the boot manager has been set up.

</para>
</footnote>.

</para>
   </sect3>

   <sect3><title>Shadow RAM</title>
<para>

Your motherboard may provide <emphasis>shadow RAM</emphasis> or BIOS
caching. You may see settings for <quote>Video BIOS Shadow</quote>,
<quote>C800-CBFF Shadow</quote>, etc. <emphasis>Disable</emphasis>
all shadow RAM.  Shadow
RAM is used to accelerate access to the ROMs on your motherboard and
on some of the controller cards. Linux does not use these ROMs once it
has booted because it provides its own faster 32-bit software in place
of the 16-bit programs in the ROMs. Disabling the shadow RAM may make
some of it available for programs to use as normal memory.  Leaving
the shadow RAM enabled may interfere with Linux access to hardware
devices.

</para>
   </sect3>

   <sect3><title>Memory Hole</title>
<para>

If your BIOS offers something like <quote>15&ndash;16 MB Memory
Hole</quote>, please disable that. Linux expects to find memory there if
you have that much RAM.

</para><para>

We have a report of an Intel Endeavor motherboard on which there is an
option called <quote>LFB</quote> or <quote>Linear Frame Buffer</quote>.
This had two settings: <quote>Disabled</quote> and <quote>1
Megabyte</quote>. Set it to <quote>1 Megabyte</quote>.
When disabled, the installation floppy was not read correctly, and the
system eventually crashed. At this writing we don't understand what's
going on with this particular device &mdash; it just worked with that
setting and not without it.

</para>
   </sect3>

<!-- no other platforms other than x86 provide this sort of thing, AFAIK -->

   <sect3><title>Advanced Power Management</title>
<para>

If your motherboard provides Advanced Power Management (APM),
configure it so that power management is controlled by APM. Disable
the doze, standby, suspend, nap, and sleep modes, and disable the hard
disk's power-down timer.  Linux can take over control of these modes,
and can do a better job of power-management than the BIOS.

</para>
   </sect3>
  </sect2>