Sometimes, especially with older CD-ROM drives, the installer may fail to boot from a CD-ROM. The installer may also — even after booting successfully from CD-ROM — fail to recognize the CD-ROM or return errors while reading from it during the installation. 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. There are two very simple things that you should try first. If the CD-ROM does not boot, check that it was inserted correctly and that it is not dirty. If the installer fails to recognize a CD-ROM, try just running the option Detect and mount CD-ROM a second time. Some DMA related issues with older CD-ROM drives are known to be resolved in this way. 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. If you cannot get the installation working from CD-ROM, try one of the other installation methods that are available. Some older CD-ROM drives do not support reading from discs that were burned at high speeds using a modern CD writer. 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). Some older CD-ROM drives do not work correctly if direct memory access (DMA) is enabled. If the CD-ROM fails to boot, try the suggestions listed below. 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. If you downloaded an iso image, check that the md5sum of that image matches the one listed for the image in the MD5SUMS file that should be present in the same location as where you downloaded the image from. $ md5sum debian-testing-i386-netinst.iso a20391b12f7ff22ef705cee4059c6b92 debian-testing-i386-netinst.iso 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. $ dd if=/dev/cdrom | \ > head -c `stat --format=%s debian-testing-i386-netinst.iso` | \ > md5sum a20391b12f7ff22ef705cee4059c6b92 - 262668+0 records in 262668+0 records out 134486016 bytes (134 MB) copied, 97.474 seconds, 1.4 MB/s 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. Switch to VT4 or view the contents of /var/log/syslog (use nano as editor) to check for any specific error messages. After that, also check the output of dmesg. Check in the output of dmesg if your CD-ROM drive was recognized. You should see something like (the lines do not necessarily have to be consecutive): 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 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 modprobe. Check that there is a device node for your CD-ROM drive under /dev/. In the example above, this would be /dev/hdc. There should also be a /dev/cdroms/cdrom0. Use the mount command to check if the CD-ROM is already mounted; if not, try mounting it manually: $ mount /dev/hdc /cdrom Check if there are any error messages after that command. Check if DMA is currently enabled: $ cd /proc/ide/hdc $ grep using_dma settings using_dma 1 0 1 rw A 1 in the first column after using_dma means it is enabled. If it is, try disabling it: $ echo -n "using_dma:0" >settings Make sure that you are in the directory for the device that corresponds to your CD-ROM drive. 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. The biggest problem for people using floppy disks to install Debian seems to be floppy disk reliability. 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. If you are having the installation stall at a particular floppy, the first thing you should do is write the image to a different 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. One user reports he had to write the images to floppy three times before one worked, and then everything was fine with the third floppy. 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. 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. 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 . Often, problems can be solved by removing add-ons and peripherals, and then trying booting again. Internal modems, sound cards, and Plug-n-Play devices can be especially problematic. 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 mem=512m. There are some common installation problems that can be solved or avoided by passing certain boot parameters to the installer. Some systems have floppies with inverted DCLs. If you receive errors reading from the floppy, even when you know the floppy is good, try the parameter floppy=thinkpad. 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 hd=cylinders,heads,sectors. If you have a very old machine, and the kernel hangs after saying Checking 'hlt' instruction..., then you should try the no-hlt boot argument, which disables this test. 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 fb=false video=vga16:off to disable the framebuffer console. Only a reduced set of languages will be available during the installation due to limited console features. See for details. 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 hw-detect/start_pcmcia=false boot parameter. You can then configure PCMCIA after the installation is completed and exclude the resource range causing the problems. 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 exclude port 0x800-0x8ff here. There is also a list of some common resource range options in the System resource settings section of the PCMCIA HOWTO. Note that you have to omit the commas, if any, when you enter this value in the installer. 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 debian-installer/probe/usb=false parameter at the boot prompt, which will prevent the modules from being loaded. There are some common installation problems that are worth mentioning. It is fairly common for &arch-title; to have two video cards in one machine, for example an ATI card and a Sun Creator 3D. In some cases, this may result in the video output getting misdirected soon after the system boots. In typical cases, the display will only show: Remapping the kernel... done Booting Linux... To work around this, you can either pull out one of the video cards, or disable the one not used during the OpenProm boot phase using a kernel parameter. For example, to disable an ATI card, you should boot the installer with video=atyfb:off. Note that you may also have to manually add this parameter to the silo configuration (edit /target/etc/silo.conf before rebooting) and, if you installed X11, modify the video driver in /etc/X11/xorg.conf. Some Sparc systems are notoriously difficult to boot from CD-ROM and even if they do boot, there may be inexplicable failures during the installation. Most problems have been reported with SunBlade systems. We recommend to install such systems by netbooting the installer. During the boot sequence, you may see many messages in the form can't find something, or something not present, can't initialize something, or even this driver release depends on something. 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 ). If you get through the initial boot phase but cannot complete the install, the menu option Save debug logs 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. Other pertinent installation messages may be found in /var/log/ during the installation, and /var/log/installer/ after the computer has been booted into the installed system. 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. 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. If you have a working Debian system, the easiest way to send an installation report is to install the installation-report and reportbug packages (aptitude install installation-report reportbug), configure reportbug as explained in , and run the command reportbug installation-reports. Alternatively you can use this template when filling out installation reports, and file the report as a bug report against the installation-reports pseudo package, by sending it to submit@bugs.debian.org. Package: installation-reports Boot method: <How did you boot the installer? CD? floppy? network?> Image version: <Full URL to image you downloaded is best> Date: <Date and time of the install> Machine: <Description of machine (eg, IBM Thinkpad R32)> Processor: Memory: Partitions: <df -Tl will do; the raw partition table is preferred> 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: <Description of the install, in prose, and any thoughts, comments and ideas you had during the initial install.> 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.