Custom kernel for Ubuntu 10.04 Live USB install

I created a persistent live USB for Ubuntu 10.04 by using usb-creator-gtk, which is a great utility! Now, I want to install a custom kernel. I created .deb packages for my custom kernel using another one of my posts here (“Building Ubuntu kernels the right way”). Then, I tried to install my custom kernel from within the live environment. This put the vmlinuz file and the modules in place, but did not create an initrd or update the syslinux bootloader. I created the initrd myself using mkinitramfs. Assuming you know how to do that. Steps for updating syslinux:

1. Copy the kernel to /cdrom/casper (and name it something compatible with vfat)
2. Repackage the initrd to be compressed with .lz

mkdir initrd-tmp
cd initrd-tmp
gzip -dc /path/to/initrd.gz | cpio -id
find . | cpio --quiet --dereference -o -H newc | lzma -7 > /path/to/new-initrd.lz

3. Copy the new initrd.lz to /cdrom/casper
4. Update /cdrom/syslinux/text.cfg.


Disabling CPU Frequency Scaling in Ubuntu Linux 10.04

Using ‘rdtsc’ to measure performance by counting CPU cycles is only useful if the CPU’s clock frequency is stable. In Ubuntu 10.04, right click a panel (e.g., the menu bar at the top of the screen) and click “Add to Panel…”. Select “CPU Frequency Scaling Monitor”. It will now appear on the panel. Click it with the left mouse button. The options should be self-explanatory. No word yet on whether settings persist across reboots (i.e., how to change the default).

One thread suggests the following:

create the file /etc/default/cpufrequtils

Inside it, place the following, obviously, change the governor and/or speeds you wish to use. When you reboot, cpufreq will read this file to determine your chosen settings. FYI: Setting speeds to 0 will set max and min to whatever your CPU supports, respectively.