Absolutely Tech

[SOLVED] kernel_thread_helper+0x7/0x10 during Ubuntu boot process

Recently, I tried installing Ubuntu on my friend’s computer. I used Maverick’s Live CD but the boot process stuck at kernel_thread_helper+0x7/0x10. I noticed a huge list of acpi errors above this message and figured it was somehow related to ACPI. To solve the problem I simply turned of ACPI.

Solving the problem in Live CD:
Insert live cd, and before the Ubuntu tries to boot into it press Esc repeatedly until you get to Ubuntu menu. Press F6 and select acpi=off and press enter. You can now press Esc again to close this sub-menu and press ‘Enter’ to boot into Live CD. This time your boot process should complete without any errors.

Solving the problem in installed system:
(Once you install Ubuntu using Live CD, you have to follow the following steps to fix this problem in your installation.)
1. In the grub menu, press ‘e’. Search for ‘quiet splash’ and add ‘acpi=off’ (without quotes) after that to make it look like ‘quiet splash acpi=off’. You’ll be able to boot in now.
2. Go to Applications->Accessories->Terminal
3. Execute:

sudo gedit /etc/default/grub

4. Find the line which says GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash” and change it to the following:
GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash acpi=off”
5. Exit gedit.
6. Execute:

sudo update-grub

7. Restart. This time you don’t have to edit anything. Ubuntu should boot without any issues.

Comments and suggestions are more than welcome.

Recovering GRUB2 after hard-drive upgrade

I upgraded to a 500GB hard-drive and installed windows 7 on it. I then moved my current ubuntu installation from the older HDD to the newer one on another partition, but of course there was no bootloader to load it. I had GRUB2 on older hard drive. I googled about how to recover GRUB2 but couldn’t find one. All I could find was solutions to fix corrupt Grub. So, I just reinstalled grub and then upgraded it to Grub2.

Here’s how to do it:

Boot into Ubuntu Live CD.
Mount the root disk (Disk on which Ubuntu is installed).

mkdir /media/root
mount /dev/sda7 /media/root

where /dev/sda7 is your disk.

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