path: root/en/boot-installer/trouble.xml

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 <sect1 id="boot-troubleshooting">
 <title>Troubleshooting the Installation Process</title>
<para>
</para>

  <sect2 arch="not-s390" id="unreliable-cd">
  <title>CD-ROM Reliability</title>
<para>

Sometimes, especially with older CD-ROM drives, the installer may fail
to boot from a CD-ROM. The installer may also &mdash; even after booting
successfully from CD-ROM &mdash; fail to recognize the CD-ROM or return
errors while reading from it during the installation.

</para><para>

There are a many different possible causes for these problems. We can
only list some common issues and provide general suggestions on how to
deal with them. The rest is up to you.

</para><para>

There are two very simple things that you should try first.

<itemizedlist>
<listitem><para>

If the CD-ROM does not boot, check that it was inserted correctly and that
it is not dirty.

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

If the installer fails to recognize a CD-ROM, try just running the option
<menuchoice> <guimenuitem>Detect and mount CD-ROM</guimenuitem> </menuchoice>
a second time. Some DMA related issues with older CD-ROM drives are known to
be resolved in this way.

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

</para><para>

If this does not work, then try the suggestions in the subsections below.
Most, but not all, suggestions discussed there are valid for both CD-ROM and
DVD, but we'll use the term CD-ROM for simplicity.

</para><para>

If you cannot get the installation working from CD-ROM, try one of the
other installation methods that are available.

</para>

  <sect3>
  <title>Common issues</title>

<itemizedlist>
  <listitem><para>

Some older CD-ROM drives do not support reading from discs that were burned
at high speeds using a modern CD writer.

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

If your system boots correctly from the CD-ROM, it does not necessarily
mean that Linux also supports the CD-ROM (or, more correctly, the controller
that your CD-ROM drive is connected to). 

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

Some older CD-ROM drives do not work correctly if <quote>direct memory
access</quote> (DMA) is enabled.

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

  </sect3>

  <sect3>
  <title>How to investigate and maybe solve issues</title>
<para>

If the CD-ROM fails to boot, try the suggestions listed below.

<itemizedlist>
  <listitem><para>

Check that your BIOS actually supports booting from CD-ROM (older systems
possibly don't) and that your CD-ROM drive supports the media you are using.

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

If you downloaded an iso image, check that the md5sum of that image matches
the one listed for the image in the <filename>MD5SUMS</filename> file that
should be present in the same location as where you downloaded the image
from.

<informalexample><screen>
$ md5sum <replaceable>debian-testing-i386-netinst.iso</replaceable>
a20391b12f7ff22ef705cee4059c6b92  <replaceable>debian-testing-i386-netinst.iso</replaceable>
</screen></informalexample>

Next, check that the md5sum of the burned CD-ROM matches as well. The
following command should work. It uses the size of the image to read the
correct number of bytes from the CD-ROM.

<informalexample><screen>
$ dd if=/dev/cdrom | \
> head -c `stat --format=%s <replaceable>debian-testing-i386-netinst.iso</replaceable>` | \
> md5sum
a20391b12f7ff22ef705cee4059c6b92  -
262668+0 records in
262668+0 records out
134486016 bytes (134 MB) copied, 97.474 seconds, 1.4 MB/s
</screen></informalexample>

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

</para><para>

If, after the installer has been booted successfully, the CD-ROM is not
detected, sometimes simply trying again may solve the problem. If you have
more than one CD-ROM drive, try changing the CD-ROM to the other drive.
If that does not work or if the CD-ROM is recognized but there are errors
when reading from it, try the suggestions listed below. Some basic knowledge
of Linux is required for this.
To execute any of the commands, you should first switch to the second
virtual console (VT2) and activate the shell there.

<itemizedlist>
  <listitem><para>

Switch to VT4 or view the contents of <filename>/var/log/syslog</filename>
(use <command>nano</command> as editor) to check for any specific error
messages. After that, also check the output of <command>dmesg</command>.

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

Check in the output of <command>dmesg</command> if your CD-ROM drive was
recognized. You should see something like (the lines do not necessarily
have to be consecutive):

<informalexample><screen>
Probing IDE interface ide1...
hdc: TOSHIBA DVD-ROM SD-R6112, ATAPI CD/DVD-ROM drive
ide1 at 0x170-0x177,0x376 on irq 15
hdc: ATAPI 24X DVD-ROM DVD-R CD-R/RW drive, 2048kB Cache, UDMA(33)
Uniform CD-ROM driver Revision: 3.20
</screen></informalexample>

If you don't see something like that, chances are the controller your CD-ROM
is connected to was not recognized or may be not supported at all. If you
know what driver is needed for the controller, you can try loading it manually
using <command>modprobe</command>.

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

Check that there is a device node for your CD-ROM drive under
<filename>/dev/</filename>. In the example above, this would be
<filename>/dev/hdc</filename>.
There should also be a <filename>/dev/cdroms/cdrom0</filename>.

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

Use the <command>mount</command> command to check if the CD-ROM is already
mounted; if not, try mounting it manually:

<informalexample><screen>
$ mount /dev/<replaceable>hdc</replaceable> /cdrom
</screen></informalexample>

Check if there are any error messages after that command.

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

Check if DMA is currently enabled:

<informalexample><screen>
$ cd /proc/<replaceable>ide</replaceable>/<replaceable>hdc</replaceable>
$ grep using_dma settings
using_dma      1       0       1       rw
</screen></informalexample>

A <quote>1</quote> in the first column after <literal>using_dma</literal>
means it is enabled. If it is, try disabling it:

<informalexample><screen>
$ echo -n "using_dma:0" >settings
</screen></informalexample>

Make sure that you are in the directory for the device that corresponds
to your CD-ROM drive.

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

If there are any problems during the installation, try checking the integrity
of the CD-ROM using the option near the bottom of the installer's main menu.
This option can also be used as a general test if the CD-ROM can be read
reliably.

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

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

  <sect2 condition="supports-floppy-boot" id="unreliable-floppies">
  <title>Floppy Disk Reliability</title>

<para>

The biggest problem for people using floppy disks to install Debian
seems to be floppy disk reliability.

</para><para>

The boot floppy is the floppy with the worst problems, because it
is read by the hardware directly, before Linux boots.  Often, the
hardware doesn't read as reliably as the Linux floppy disk driver, and
may just stop without printing an error message if it reads incorrect
data. There can also be failures in the driver floppies, most of which
indicate themselves with a flood of messages about disk I/O errors.

</para><para>

If you are having the installation stall at a particular floppy, the first
thing you should do is write the image to a <emphasis>different</emphasis>
floppy and see if that solves the problem. Simply reformatting the old
floppy may not be sufficient, even if it appears that the floppy was
reformatted and written with no errors. It is sometimes useful to try
writing the floppy on a different system.

</para><para>

One user reports he had to write the images to floppy
<emphasis>three</emphasis> times before one worked, and then
everything was fine with the third floppy.

</para><para>

Normally you should not have to download a floppy image again, but if you
are experiencing problems it is always useful to verify that the images
were downloaded correctly by verifying their md5sums.

</para><para>

Other users have reported that simply rebooting a few times with the
same floppy in the floppy drive can lead to a successful boot. This is
all due to buggy hardware or firmware floppy drivers.

</para>
  </sect2>

  <sect2><title>Boot Configuration</title>

<para>

If you have problems and the kernel hangs during the boot process,
doesn't recognize peripherals you actually have, or drives are not
recognized properly, the first thing to check is the boot parameters,
as discussed in <xref linkend="boot-parms"/>.

</para><para>

If you are booting with your own kernel instead of the one supplied
with the installer, be sure that <userinput>CONFIG_DEVFS</userinput> is set in
your kernel.  The installer requires
<userinput>CONFIG_DEVFS</userinput>.

</para><para>

Often, problems can be solved by removing add-ons and peripherals, and
then trying booting again.  <phrase arch="x86">Internal modems, sound
cards, and Plug-n-Play devices can be especially problematic.</phrase>

</para><para>

If you have a large amount of memory installed in your machine, more
than 512M, and the installer hangs when booting the kernel, you may
need to include a boot argument to limit the amount of memory the
kernel sees, such as <userinput>mem=512m</userinput>.

</para>
  </sect2>

  <sect2 arch="x86" id="i386-boot-problems">
  <title>Common &arch-title; Installation Problems</title>
<para>

There are some common installation problems that can be solved or avoided by
passing certain boot parameters to the installer.

</para><para>

Some systems have floppies with <quote>inverted DCLs</quote>. If you receive
errors reading from the floppy, even when you know the floppy is good,
try the parameter <userinput>floppy=thinkpad</userinput>.

</para><para>

On some systems, such as the IBM PS/1 or ValuePoint (which have ST-506
disk drivers), the IDE drive may not be properly recognized.  Again,
try it first without the parameters and see if the IDE drive is
recognized properly.  If not, determine your drive geometry
(cylinders, heads, and sectors), and use the parameter
<userinput>hd=<replaceable>cylinders</replaceable>,<replaceable>heads</replaceable>,<replaceable>sectors</replaceable></userinput>.

</para><para>

If you have a very old machine, and the kernel hangs after saying
<computeroutput>Checking 'hlt' instruction...</computeroutput>, then
you should try the <userinput>no-hlt</userinput> boot argument, which
disables this test.

</para><para>

If your screen begins to show a weird picture while the kernel boots,
eg. pure white, pure black or colored pixel garbage, your system may
contain a problematic video card which does not switch to the
framebuffer mode properly.  Then you can use the boot parameter
<userinput>fb=false video=vga16:off</userinput> to disable the framebuffer
console. Only the English
language will be available during the installation due to limited
console features. See <xref linkend="boot-parms"/> for details.

</para>

  <sect3>
  <title>System Freeze During the PCMCIA Configuration Phase</title>
<para>

Some laptop models produced by Dell are known to crash when PCMCIA device
detection tries to access some hardware addresses. Other laptops may display
similar problems. If you experience such a problem and you don't need PCMCIA
support during the installation, you can disable PCMCIA using the
<userinput>hw-detect/start_pcmcia=false</userinput> boot parameter. You can
then configure PCMCIA after the installation is completed and exclude the
resource range causing the problems.

</para><para>

Alternatively, you can boot the installer in expert mode. You will
then be asked to enter the resource range options your hardware
needs. For example, if you have one of the Dell laptops mentioned
above, you should enter <userinput>exclude port
0x800-0x8ff</userinput> here. There is also a list of some common
resource range options in the <ulink
url="http://pcmcia-cs.sourceforge.net/ftp/doc/PCMCIA-HOWTO-1.html#ss1.12">System
resource settings section of the PCMCIA HOWTO</ulink>. Note that you
have to omit the commas, if any, when you enter this value in the
installer.

</para>
   </sect3>

   <sect3>
   <title>System Freeze while Loading the USB Modules</title>
<para>

The kernel normally tries to install USB modules and the USB keyboard driver
in order to support some non-standard USB keyboards. However, there are some
broken USB systems where the driver hangs on loading. A possible workaround
may be disabling the USB controller in your mainboard BIOS setup. Another option
is passing the <userinput>debian-installer/probe/usb=false</userinput> parameter
at the boot prompt, which will prevent the modules from being loaded.

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

  <sect2 id="kernel-msgs">
  <title>Interpreting the Kernel Startup Messages</title>

<para>

During the boot sequence, you may see many messages in the form
<computeroutput>can't find <replaceable>something</replaceable>
</computeroutput>, or <computeroutput>
<replaceable>something</replaceable> not present</computeroutput>,
<computeroutput>can't initialize <replaceable>something</replaceable>
</computeroutput>, or even <computeroutput>this driver release depends
on <replaceable>something</replaceable> </computeroutput>.
Most of these messages are harmless. You
see them because the kernel for the installation system is built to
run on computers with many different peripheral devices. Obviously, no
one computer will have every possible peripheral device, so the
operating system may emit a few complaints while it looks for
peripherals you don't own. You may also see the system pause for a
while. This happens when it is waiting for a device to respond, and
that device is not present on your system. If you find the time it
takes to boot the system unacceptably long, you can create a
custom kernel later (see <xref linkend="kernel-baking"/>).

</para>
  </sect2>


  <sect2 id="problem-report">
  <title>Reporting Installation Problems</title>
<para>

If you get through the initial boot phase but cannot complete the install,
the menu option <guimenuitem>Save debug logs<guimenuitem> may be helpful.
It lets you store system error logs and configuration information from the
installer to a floppy, or download them using a web browser.

This information may provide clues as to what went wrong and how to
fix it.  If you are submitting a bug report you may want to attach
this information to the bug report.

</para><para>

Other pertinent installation messages may be found in
<filename>/var/log/</filename> during the
installation, and <filename>/var/log/installer/</filename>
after the computer has been booted into the installed system.

</para>
  </sect2>

  <sect2 id="submit-bug">
  <title>Submitting Installation Reports</title>
<para>

If you still have problems, please submit an installation report. We also
encourage installation reports to be sent even if the installation is
successful, so that we can get as much information as possible on the largest
number of hardware configurations. 

</para><para>

Note that your installation report will be published in the Debian Bug
Tracking System (BTS) and forwarded to a public mailing list. Make sure that
you use an E-Mail address that you do not mind being made public.

</para><para>

If you have a working Debian system, the easiest way to send an installation
report is to install the installation-report and reportbug packages
(<command>apt-get install installation-report reportbug</command>) and run
the command <command>reportbug installation-report</command>.

</para><para>

Alternatively you can use this template when filling out
installation reports, and file the report as a bug report against the
<classname>installation-reports</classname> pseudo package, by sending it to
<email>submit@bugs.debian.org</email>.

<informalexample><screen>
Package: installation-reports

Boot method: &lt;How did you boot the installer? CD? floppy? network?&gt;
Image version: &lt;Full URL to image you downloaded is best&gt;
Date: &lt;Date and time of the install&gt;

Machine: &lt;Description of machine (eg, IBM Thinkpad R32)&gt;
Processor:
Memory:
Partitions: &lt;df -Tl will do; the raw partition table is preferred&gt;

Output of lspci -nn and lspci -vnn:

Base System Installation Checklist:
[O] = OK, [E] = Error (please elaborate below), [ ] = didn't try it

Initial boot:           [ ]
Detect network card:    [ ]
Configure network:      [ ]
Detect CD:              [ ]
Load installer modules: [ ]
Detect hard drives:     [ ]
Partition hard drives:  [ ]
Install base system:    [ ]
Clock/timezone setup:   [ ]
User/password setup:    [ ]
Install tasks:          [ ]
Install boot loader:    [ ]
Overall install:        [ ]

Comments/Problems:

&lt;Description of the install, in prose, and any thoughts, comments
      and ideas you had during the initial install.&gt;
</screen></informalexample>

In the bug report, describe what the problem is, including the last
visible kernel messages in the event of a kernel hang.  Describe the
steps that you did which brought the system into the problem state.

</para>
  </sect2>
 </sect1>