Hybrid image mode for Knoppix 8.0
Improving Bootability
Knoppix includes a tiny "boot-only" ISO image in the KNOPPIX folder, which allows you to boot computers that have a USB but cannot boot from it because of a BIOS limitation, to first boot kernel and initial ramdisk from the tiny (20MB) CD version. This then searches for the KNOPPIX folder in all attached drives containing the main system files. This also may be a good workaround for non-hybrid booting BIOSes.
For a UEFI boot, I included a FAT32 partition image with a signed 64-bit pre-bootloader, which then chainloads a special EFI version of syslinux (the disk bootloader) for starting kernel and initial ramdisk in this boot mode.
In theory, computers that can only boot via UEFI should find this image as a UEFI partition on the DVD, as well as on flash disk, and boot from there. In UEFI "secure" mode, a dialog will ask for permission to enroll the bootloader's checksum in the UEFI firmware to enable execution of the "foreign" OS.
With secure mode turned off, UEFI will start the boot screen normally (just without the usual boot splash graphics; we are not in VGA mode anymore).
Image Layout
Figure 6 shows the old DVD-only layout on the left, the new hybrid DVD+Flash layout in the middle, and the "improved" format on the right which allows you to write on the first partition again. The latter is still created by the included flash-knoppix
and is not usable for DVDs.
Only the enhanced layout allows to use special Knoppix features, such as changing boot options (the first partition needs to be writable for that) and encryption of the data overlay on the last partition.
Regaining Unclaimed Space
You may have noted the tiny (4MB) Linux partition at the end of the hybrid image format. This is a trick that allows me to adjust the last partition automatically with no interaction during the first boot of a USB flash disk that was freshly installed from the hybrid image using dd
or Disk Imager.
During the first boot of Knoppix in the hybrid layout, the idea is to:
- Expand the last (
KNOPPIX-DATA
) partition of the disk to the maximum size. - Expand the filesystem (ReiserFS) on the partition to also use the now available full capacity.
- Continue booting normally with the adjusted
KNOPPIX-DATA
partition as a writable overlay for personal data.
As seen with other distros, there is usually a reboot issued after modifying partitions. I'm trying to avoid this by letting the Knoppix ramdisk do the adjustment before actually mounting the partition, so the kernel can reread the new partition table without problems.
Even if rereading the partition table fails (you never know…), the data partition's start is unchanged, because it was already there, so it can already be used regardless of a temporary "wrong" partition size. Somewhat to my surprise, this works perfectly on all tested computers, so you have a full-sized data partition for your installations and configuration changes immediately from the first boot.
The relevant section in the initial ramdisk script makes sure that only a partition labeled as KNOPPIX-DATA
will be expanded, so no other partitions are affected accidentally.
« Previous 1 2 3 Next »
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
Juno Computers Launches Another Linux Laptop
If you're looking for a powerhouse laptop that runs Ubuntu, the Juno Computers Neptune 17 v6 should be on your radar.
-
ZorinOS 17.1 Released, Includes Improved Windows App Support
If you need or desire to run Windows applications on Linux, there's one distribution intent on making that easier for you and its new release further improves that feature.
-
Linux Market Share Surpasses 4% for the First Time
Look out Windows and macOS, Linux is on the rise and has even topped ChromeOS to become the fourth most widely used OS around the globe.
-
KDE’s Plasma 6 Officially Available
KDE’s Plasma 6.0 "Megarelease" has happened, and it's brimming with new features, polish, and performance.
-
Latest Version of Tails Unleashed
Tails 6.0 is based on Debian 12 and includes GNOME 43.
-
KDE Announces New Slimbook V with Plenty of Power and KDE’s Plasma 6
If you're a fan of KDE Plasma, you'll be thrilled to hear they've announced a new Slimbook with an AMD CPU and the latest version of KDE Plasma desktop.
-
Monthly Sponsorship Includes Early Access to elementary OS 8
If you want to get a glimpse of what's in the pipeline for elementary OS 8, just set up a monthly sponsorship to help fund its continued existence.
-
DebConf24 to be Held in South Korea
Busan will be the location of the latest DebConf running July 28 through August 4
-
Fedora Unleashes Atomic Desktops
Fedora has combined its solid distribution with rpm-ostree system to make it possible to deliver a new family of Fedora spins, called Fedora Atomic Desktops.
-
Bootloader Vulnerability Affects Nearly All Linux Distributions
The developers of shim have released a version to fix numerous security flaws, including one that could enable remote control execution of malicious code under certain circumstances.