Contents
How to use Ubuntu kernel in Knoppix
How I came up with
this and why you may need it
Outline of steps
needed to install Ubuntu kernel in Knoppix
Preparing USB flash
drive with Knoppix
Getting Ubuntu kernel
images
Recreating modules.dep
for Ubuntu kernel modules
Compiling out-of-tree
cloop kernel module
Appending Ubuntu
kernel modules to custom minirt.gz
Adding Ubuntu kernel
to syslinux config
Appendix A – Knoppix
minirt init script outline
Appendix B – Ubuntu
kernel in Knoppix that is fully HDD-installed on reiserfs partition with grub
Appendix C – how to
get Ubuntu kernel source to embed needed kernel modules
How to use Ubuntu kernel in Knoppix
How I came up with this and why you may need it
I am a Knoppix guy through and through and
I was very disappointed that Knoppix 8.2 x86 with 4.16.5 kernel froze on my DEXP
310 Intel Baytrail tablet. I read bko109051 (which may give nightmares to the
unprepared), added intel_idle.max_cstate=1, it prolonged working time a bit but
eventually it froze all the same. I unpacked kernel source 4.16.5 which is preinstalled
in Knoppix, tried backported Mika v3 patch and rebuilt kernel using make-kpkg.
It worked a little longer but still froze. Googling a little more led me to
Linuxium project, where I found respun Ubuntu 16.04.4 x64 ISO. I tried to boot
it and the miracle happened – it was working pretty stable on my Dexp Bay Trail
tablet! So I downloaded latest official LUbuntu with HWE lubuntu-18.04.2-desktop-i386.iso
and it worked stable as well.
I copied Ubuntu kernel and modules to
Knoppix and tried to boot it but no dice – most drivers that are built-in in
Knoppix are compiled as modules in Ubuntu. After 2 days of brutal Knoppix hacking/troubleshooting
I came victorious.
You may want to use Ubuntu kernel in
Knoppix because:
- Stock Knoppix kernel freezes on your system but Ubuntu somehow works and you don’t want to fully switch to Ubuntu
- You want latest kernel with latest drivers from Ubuntu HWE
To use the following method stock Knoppix
kernel should work at least for some time sufficient to install Ubuntu
kernel/module packages and to compile cloop kernel module (described later). On
my tablet it worked longer in text mode boot with ‘knoppix
intel_idle.max_cstate=1 2’. If Knoppix freezes at once even in text mode boot
and you don’t have enough time to do anything described below, you may want to
boot Knoppix USB flash at another PC or under Vmware/Virtualbox (may connect
USB flash drive to VM and boot it from KNOPPIX/bootonly.iso if it does not
support booting from USB).
Outline of steps needed to install Ubuntu kernel in Knoppix
- Get Ubuntu kernel image/module/header packages
- Prepare USB flash drive with Knoppix 8.2.
- Boot Knoppix USB flash drive and install Ubuntu kernel packages
- Recreate modules.dep for Ubuntu kernel modules to make sure that graphics modules can be found by modprobe during boot to init graphics console (or else screen might remain blank on UEFI systems)
- Compile out-of-tree cloop kernel module using Ubuntu kernel headers
- Append Ubuntu kernel modules usb-storage, nls_iso8859-1.ko, isofs, reiserfs, cloop, aufs to custom minirt_ub.gz (they are needed to access USB drive, mount FAT partition, mount and unify KNOPPIX and KNOPPIX1 compressed filesystems)
- Add Ubuntu kernel with custom minirt_ub.gz to syslinux.cfg (for legacy BIOS systems) or syslnx32.cfg/syslnx64.cfg (for UEFI systems)
Preparing USB flash drive with Knoppix
Download Knoppix ISO, boot it and install it to USB flash drive using flash-knoppix (dump of ISO to flash
drive with dd in Linux or rufus in Windows is not tested by me as it has strange partition layout but YMMV). Resulting USB drive must have:
- first FAT KNOPPIX partition with boot files and compressed filesystem files
- second reiserfs KNOPPIX-DATA partition which will be extended to fill all available space on USB flash drive
Getting Ubuntu kernel images
To get .deb files for Ubuntu kernel you may
- repack installed packages from running Ubuntu (if you have Ubuntu ISO and have no internet connection)
- download prebuilt packages (look up package filenames in /var/lib/apt/lists).
The following examples are for 4.18.0-15-generic
kernel which is in lubuntu 18.04.2.
To repack/recreate debs from installed
packages boot Ubuntu and use
sudo dpkg-repack {package name}
sudo dpkg-repack {package name}
Package name
|
Unpacked Size
|
Comment
|
linux-headers-4.18.0-15
|
69.6 Mb
|
main kernel headers – needed to compile
cloop module
|
linux-headers-4.18.0-15-generic
|
7.5 Mb
|
additional headers symlink and Module.symvers
– needed to compile cloop module
|
linux-image-4.18.0-15-generic
|
7.9 Mb kernel image
|
cannot be repacked with dpkg-repack – do
not install this package in Knoppix as it depends on Ubuntu base package, will
be marked broken and will give trouble with synaptic, instead unpack it
manually or get kernel from Ubuntu ISO – vmlinuz file in casper dir, rename
it vmlinuz-4.18.0-15-generic and put to /boot/syslinux dir on Knoppix USB FAT
partition
|
linux-modules-4.18.0-15-generic
|
41.3 Mb
|
base modules, has aufs.ko
|
linux-modules-extra-4.18.0-15-generic
|
116 Mb
|
extra modules, has graphics modules and also
reiserfs.ko
|
If you want to download prebuilt packages
find urls for them in /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_bionic-updates_main_binary-i386_Packages
(Far in Windows may open squashfs file on
Ubuntu ISO)
e.g.
Package: linux-image-4.18.0-15-generic
Architecture: i386
Version: 4.18.0-15.16~18.04.1
Filename: pool/main/l/linux-hwe/linux-image-4.18.0-15-generic_4.18.0-15.16~18.04.1_i386.deb
…
Architecture: i386
Version: 4.18.0-15.16~18.04.1
Filename: pool/main/l/linux-hwe/linux-image-4.18.0-15-generic_4.18.0-15.16~18.04.1_i386.deb
…
So full url will be http://archive.ubuntu.com/ubuntu/pool/main/l/linux-hwe/linux-image-4.18.0-15-generic_4.18.0-15.16~18.04.1_i386.deb
Recreating modules.dep for Ubuntu kernel modules
Now that all kernel modules are installed run
sudo
depmod 4.18.0-15-generic
to recreate modules.dep. It is needed if modules.dep was truncated (may happen if installed from dpkg-repacked packages) and missing lines with dependencies for graphics modules (DRM compiled as module in ubuntu). If you don’t do it and modules.dep does not have dependencies for needed graphics modules, Knoppix may boot Ubuntu kernel and may work but kernel DRM will have problems with graphics init during boot as modprobe in /etc/init.d/knoppix-autoconfig will fail to load nvidia / i915 modules, for example:
- On my old Athlon 64 PC with Nvidia card (needs nouveau kernel module) Knoppix starts Ubuntu kernel and works OK, but uses text console and framebuffer Xorg graphics is not accelerated e.g. no compiz;
- On my Dexp Intel Baytrail UEFI tablet (needs i915 kernel module) it cannot init graphics console at all - no Knoppix big ASCIIart banner with kernel/CPU info below and it cannot exit the UEFI black screen.
Compiling out-of-tree cloop kernel module
Knoppix needs cloop and aufs kernel modules
which are not part of vanilla kernel. aufs module is already in ubuntu kernel
(fs/aufs/aufs.ko), so you need to compile only missing cloop module.
To build out-of-tree cloop module you need:
- Ubuntu kernel headers (full kernel source is not needed)
- cloop.c and cloop.h from Knoppix kernel source (it is in /usr/src, unpack to /tmp and files are in drivers/block dir)
- Makefile (Check and modify KERNEL_DIR in Makefile to match Ubuntu kernel version):
#!/usr/bin/make
MACHINE=$(shell uname -m)
ifndef KERNEL_DIR
# If building under running Ubuntu kernel
#KERNEL_DIR:=/lib/modules/`uname -r`/build
# If building under running Knoppix kernel
KERNEL_DIR:=/lib/modules/4.18.0-15-generic/build
endif
MODULE:=cloop.ko
module: $(MODULE)
# For Kernel >= 2.6, we now use the "recommended" way to build kernel modules
obj-m := cloop.o
$(MODULE): cloop.c cloop.h
@echo "Building Kernel module"
$(MAKE) modules -C $(KERNEL_DIR) M=$(CURDIR)
MACHINE=$(shell uname -m)
ifndef KERNEL_DIR
# If building under running Ubuntu kernel
#KERNEL_DIR:=/lib/modules/`uname -r`/build
# If building under running Knoppix kernel
KERNEL_DIR:=/lib/modules/4.18.0-15-generic/build
endif
MODULE:=cloop.ko
module: $(MODULE)
# For Kernel >= 2.6, we now use the "recommended" way to build kernel modules
obj-m := cloop.o
$(MODULE): cloop.c cloop.h
@echo "Building Kernel module"
$(MAKE) modules -C $(KERNEL_DIR) M=$(CURDIR)
To compile cloop.ko kernel module run
make
module
Appending Ubuntu kernel modules to custom minirt.gz
Copy the following kernel modules to
temporary modules dir. Ubuntu default initrd (casper/initrd in Ubuntu
ISO) has many kernel modules in /lib/modules/4.18.0-15-generic but Knoppix’s minirt.gz
init script will not find them – it will load modules only from modules
dir.
Kernel module
|
Subdir where to get it (root modules dir is /lib/modules/4.18.0-15-generic)
|
Purpose
|
usb-storage.ko
|
kernel/drivers/usb/storage
|
for USB flash drive access
|
nls_iso8859-1.ko
|
kernel/fs/nls
|
for VFAT mount, this iocharset is default
in Ubuntu kernel (see CONFIG_FAT_DEFAULT_IOCHARSET in kernel .config file),
Knoppix uses UTF8 by default
|
isofs.ko
|
kernel/fs/isofs
|
iso9660 support for KNOPPIX and KNOPPIX1
cloop mount
|
reiserfs.ko
|
kernel/fs/reiserfs
|
default FS in Knoppix, module is in
linux-modules-extra .deb package
|
aufs.ko
|
fs/aufs
|
for filesystems unification.
Can also be loaded from KNOPPIX/modules dir on Knoppix USB drive FAT partition |
cloop.ko
|
where you just compiled it
|
for compressed ISO filesystems mount.
Can also be loaded from KNOPPIX/modules dir on Knoppix USB drive FAT partition |
So we need to create gzipped cpio archive with listed above modules and append it to custom minirt_ub.gz:
- mkdir modules - create it anywhere e.g. in /tmp, but it must be named modules
- Copy modules from table above to newly created temporary modules subdir
- Create gzipped cpio archive that will be
appended to custom minirt.gz (run command from dir where you created modules subdir)
ls -1 ./modules | sed 's/^/\.\/modules\//' | cpio -H newc -o | gzip > ramdisk_modules.gz - Copy ramdisk_modules.gz to /boot/syslinux dir on Knoppix USB FAT partition (it will be mounted under /mnt-system if you are running Knoppix)
- copy knoppix's default minirt.gz as custom minirt_ub.gz
in /boot/syslinux dir and append ramdisk_modules.gz to it:
cat minirt.gz ramdisk_modules.gz > minirt_ub.gz
Adding Ubuntu kernel to syslinux config
Must use updated minirt for ubuntu kernel
boot in syslinux.cfg (for legacy BIOS systems) or
syslnx32.cfg/syslnx64.cfg (for UEFI systems):
LABEL
knoppix_ub
KERNEL vmlinuz-4.18.0-15-generic
APPEND lang=en apm=power-off initrd=minirt_ub.gz nomce hpsa.hpsa_allow_any=1 loglevel=1
KERNEL vmlinuz-4.18.0-15-generic
APPEND lang=en apm=power-off initrd=minirt_ub.gz nomce hpsa.hpsa_allow_any=1 loglevel=1
If you did everything correctly you may reboot, press TAB at syslinux prompt and type knoppix_ub to boot Ubuntu kernel! If everything is working you may set knoppix_ub to boot by default.
Appendix A – Knoppix minirt init script outline
To debug init script add 'debug' to kernel
start options (may not be visible on UEFI systems)
---------------------------------------------------------------------------------
Knoppix init:
init script has many utility functions
at start of script
# Main
ASCIIart banner
load_modules - loads /modules/*.ko
/modules/scsi/*.ko that are in ramdisk
Tries NFS
# Print kernel info
# Print CPU info
mounts ramdisk
Looks for knoppix in local drives
if [ -z "$FOUND_KNOPPIX" -a
-z "$TSCLIENT" ]; then
(not NFS)
(no root=/dev/... kernel option
specified e.g. Knoppix is not fully installed on HDD)
if /sys/bus/usb/drivers/usb-storage
tries findknoppix for local
partitions (it mounts them under /mnt-system)
Will print red message (NOTFOUND
var) if no partition with knoppix and/or if usb-storage module not loaded
checkbootparam "debug"
&& debugshell "Past mounting /mnt-system."
...
if mountknoppix; then # compressed
mountknoppix checks cloop and aufs
grep -q cloop /proc/devices ||
insmod /mnt-system/"$knoppix_dir"/modules/cloop.ko preload=32 ||
return 2
grep -q aufs /proc/filesystems ||
insmod /mnt-system/"$knoppix_dir"/modules/aufs.ko || return 3
Appendix B – Ubuntu kernel in Knoppix that is fully HDD-installed on reiserfs partition with grub
·
Install ubuntu kernel packages
·
take casper/initrd from ubuntu iso/flash (39 mb,
it has all needed modules including reiserfs)
·
add to /boot/grub/menu.lst
title
Ubuntu Kernel
root
(hd0,1)
kernel
/boot/vmlinuz-4.18.0-15-generic root=/dev/sda2 rw
initrd
/boot/initrd <<<<---- this is casper/initrd from ubuntu
iso/flash
Appendix C – how to get Ubuntu kernel source to embed needed kernel modules
Ubuntu kernel versioning is in mapping
table http://people.canonical.com/~kernel/info/kernel-version-map.html. So linux-image-4.18.0-15-generic (4.18.0-15.16~18.04.1) corresponds
to 4.18.20 mainline kernel (https://mirrors.edge.kernel.org/pub/linux/kernel/v4.x/linux-4.18.20.tar.xz).
Ubuntu kernel source differs from
corresponding mainline kernel so you need to get Ubuntu kernel source
package - use apt-get source <linux-image….> in running Ubuntu or
find source package name in /var/lib/apt/lists e.g. http://archive.ubuntu.com/ubuntu/pool/main/l/linux-hwe/linux-source-4.18.0_4.18.0-15.16~18.04.1_all.deb and download it manually.
To rebuild Knoppix-like monolithic kernel
with cloop and other needed modules:
·
Copy cloop.c and cloop.h to drivers/block in
kernel source and add cloop.o in that dir’s Makefile
obj-$(CONFIG_BLK_DEV_LOOP) += loop.o cloop.o
obj-$(CONFIG_BLK_DEV_LOOP) += loop.o cloop.o
·
Configure all modules listed in tables above as
built-in
