Knowing Knoppix/Advanced startup options

“There is only one satisfying way to boot a computer.” -- J. H. Goldfuss

OverviewEdit

This section explains the bootup options for Knoppix. Use these options to fine-tune Knoppix for your hardware and speed it up.

Enabling DMAEdit

The first and foremost way to make Knoppix run faster that almost everyone can use is to enable DMA. It stands for Direct Memory Access. It improves the speed of hard disk drives and it can also help CD-ROM drives. DMA is not supported on all computers, so Knoppix turns it off by default. To enable DMA, add 'dma' to your boot command, for example:

knoppix lang=uk dma

To test the speed of the hard disk drive, click the Knoppix menu, choose “Root Shell” and enter:

hdparm -t /dev/hda

Replace “hda” with the device name of your hard drive appropriately. After a pause of about 3 seconds, you will get a little report that will tell you how fast your hard drive reads data. DMA makes a pretty big difference. For example, look at these sample test results:

Drive Without DMA With DMA
Seagate Barracuda 7200 RPM IDE 8.5 MB/sec 26.8 Mb/sec

If you only have a single CD driveEdit

Knoppix takes over your CD drive and you can't eject it during your session. What if you want to use the CD drive for something else? For example, you may want to create CDs using a CD-ReWritable drive. If you only have one CD drive, this will be a problem.

Luckily, there is a solution. It is possible to run Knoppix from a hard drive or RAM, freeing up the CD drive for other tasks.

Transferring to a hard disk partitionEdit

Transferring to a hard disk partition means copying the CD contents onto a hard disk. This is called “copying the CD image”. Once this is done, Knoppix starts in the normal way but from the hard drive instead the CD-ROM drive.

This gives improved performance, because hard disk drives are generally much faster than CD-ROM drives. It also frees up your CD-ROM drive for other tasks. It does not affect the existing files on the hard drive. All it does is use up hard drive space, which can be reclaimed later.

To transfer to a hard disk partition, you need:

  • An MS-DOS, FAT or Linux formatted hard disk partition.
    NTFS (native Windows NT/2000/XP) partitions cannot be used.
  • At least 700 Mb free space on the partition.

At the boot prompt, enter this command. Replace “device” with the device name of the hard disk partition that you want to use.

knoppix tohd=device

For example, suppose you have Windows 98. You probably have Windows installed on the first partition of the primary master IDE drive. In this case, use:

knoppix tohd=/dev/hda1

Knoppix will start from CD, copy itself to the specified device and then continue loading from there. You can then take the Knoppix CD out of the drive.

Re-using an existing imageEdit

You only need to copy the CD image to the hard disk once. Next time, you can read back from the hard disk, without having to copy the CD image again.

At the boot prompt, enter this command. Replace “device” with the device name of the hard disk partition where the Knoppix CD image is located.

knoppix fromhd=device

For example:

knoppix fromhd=/dev/hda1

Knoppix will start from CD, pick up the CD image from the specified device and continue loading. You can then take the Knoppix CD out of the drive.

Deleting the imageEdit

In Windows, remove the “KNOPPIX” directory from the hard drive using Windows Explorer. This will give back the hard drive space occupied by the CD image.

Transferring to RAMEdit

If you have 828 Mb or more of RAM, you can copy the Knoppix CD image to RAM. After an initial wait, transferring to RAM gives dramatically improved performance, and the Knoppix CD is not needed. You need 828 Mb of RAM because the first 700 Mb is used for the CD image. The remaining 128 Mb is used for the system and applications.

At the boot prompt, enter this command:

knoppix toram

Knoppix will start from CD, transfer the CD image to RAM, and continue loading. Once transfer to RAM has completed, you can take the Knoppix CD out of the drive.

More hardware optionsEdit

These options let you fine-tune Knoppix for your particular hardware. They can be combined in any order. For example, to start Knoppix with the US language/keyboard, a wheel mouse, a screen resolution of 800x600 and Direct Memory Access (DMA) enabled for hard drives, type this at the boot prompt:

knoppix lang=uk wheelmouse screen=800x600 dma

Knoppix assumes you have a laptop. It starts up with PCMCIA (credit card adapter) interface support enabled by default. If you have a desktop computer, rather than a laptop, you can improve performance slightly by typing the “nopcmcia” option at the boot prompt. For example, to start the computer with the US locale, a wheel mouse, a screen resolution of 1024x768, and no PCMCIA:

knoppix lang=us wheelmouse screen=1024x768 nopcmcia

If you have less than 128 Mb RAMEdit

After loading the kernel and the base system, Knoppix looks to see how much RAM is left. The kernel and the base system takes about 20 Mb of RAM. The remainder is called free RAM, or available RAM.

Knoppix checks to see if there is a Linux swap partition available. You may have a swap partition if you have previously installed Linux on the hard disk. If so, Knoppix will use the existing swap partition automatically.

If there is less than 80,000 Kb free RAM, Knoppix will prompt you to create a swap file. A swap file lets you use part of the hard disk as if it were RAM.

This trick lets you run Knoppix in full, even when you have less than 128 Mb RAM. For example, it is possible to run Knoppix successfully on a computer with only 64 Mb of RAM. However, you pay a performance penalty, because swap is much slower than physical RAM.

To create a swap file, you need a hard disk with at least one partition that is formatted with the FAT filesystem. NTFS formatted partitions cannot be used.

  1. Start Knoppix in the usual way.
    Knowing Knoppix (If you have less than 128 Mb RAM 1).png
  2. You will get a message that says, “There are only X Kb of RAM available in your computer”.
  3. Press Enter.
  4. Knoppix will search for an available FAT formatted partition. If there is more than one, Knoppix will choose the last available partition. You will be asked if you want to create a swap file on the partition that Knoppix has selected.
    Knowing Knoppix (If you have less than 128 Mb RAM 2).png
  5. Using the arrow keys on the keyboard, choose “Yes”, then press Enter.
  6. You will be asked how big a swap file you want to create. You need a swap file that is large enough to take the free RAM + swap file total to at least 80,000 Kb.
  7. Type the size of the swap file you wish to create. In this example, it says there is 49,152 Kb of physical RAM free. The suggested swap file size of 60 Mb will bring the free total to 108 Mb.
    Knowing Knoppix (If you have less than 128 Mb RAM 3).png
  8. Press Enter.
  9. Wait for a moment while Knoppix creates the swap file.
    Knowing Knoppix (If you have less than 128 Mb RAM 4).png
  10. Press Enter to continue loading Knoppix.
Tip
Next time you start Knoppix, it will detect and use the swap file automatically.
To remove the swap file and reclaim the disk space it occupies, exit Knoppix, start Windows, then delete the file called “knoppix.swp” using Windows Explorer.
Last modified on 10 January 2013, at 00:04