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I tried loading a live disk of Ubuntu 12.04 on my XP computer and it keeps repeating "CPU#0 stuck for x seconds." Can someone please help me?

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  • Have you made sure the LiveCD downloaded OK by comparing the MD5 checkum published at Ubuntu's website matches the MD5 checksum of the ISO once downloaded? help.ubuntu.com/community/HowToMD5SUM explains how. If that's OK, please check the ISO by starting the process to boot into it then pressing {Esc} repeatedly; the menu which follows has an item, "Check Disk for Defects" - run that to make sure it burned OK.
    – K7AAY
    Jan 7, 2014 at 21:01
  • Can you add the output of dmesg | grep soft, and uname -r to your question?
    – Mitch
    Jan 7, 2014 at 21:09
  • Yes, click on the edit link underneath the tags - it's OK if adding the stuff Mitch asked for makes the question long.
    – K7AAY
    Jan 7, 2014 at 21:49

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The Linux kernel has a process which monitors each CPU on the system.

There are special interrupt(s) in the kernel. This interrupt(s) function calls a soft-lockup counter, it will compare the current time stamp with the specific kernel CPU data structure time information. If it looks like the current time stamp is greater than the defined threshold (in seconds) later as compared to the stored time stamp, it is assumed that the monitoring process or watchdog thread(s) have not executed in a respectable amount of time.

Why or how can a CPU soft lock occur? How can a CPU get locked if the kernel is carefully scheduling CPU access? Basically any poorly written code that loops a lot or infinitely, would own a CPU and get some priority. It can be a programming problem or 3rd party software.

Locking issues in drivers. Even kernel bugs in important drivers or the scheduler. A scheduler could tell schedule a driver routine to run and if that driver has problems and doesn’t check on it, that driver routine could own or hog that CPU for a longtime. By definition as described above, the watchdog would catch this and issue a soft lockup alert.

Soft lockups mostly hang a CPU and possibly your system temporarily.

A kernel update may fix the problem. To update the kernel, just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command(s) below:

for 32-bit system:

wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.11-saucy/linux-headers-3.11.0-031100-generic_3.11.0-031100.201309021735_i386.deb
wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.11-saucy/linux-headers-3.11.0-031100_3.11.0-031100.201309021735_all.deb
wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.11-saucy/linux-image-3.11.0-031100-generic_3.11.0-031100.201309021735_i386.deb

for 64-bit system:

wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.11-saucy/linux-headers-3.11.0-031100-generic_3.11.0-031100.201309021735_amd64.deb
wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.11-saucy/linux-headers-3.11.0-031100_3.11.0-031100.201309021735_all.deb
wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.11-saucy/linux-image-3.11.0-031100-generic_3.11.0-031100.201309021735_amd64.deb

For both 32-bit & 64-bit, run below command to install them:

sudo dpkg -i linux-headers-3.11.0*.deb linux-image-3.11.0*.deb

Once installed, restart your computer!

If you have problem with this kernel, run below command to remove it:

sudo apt-get purge linux-image-3.11.0*

Sources:Linux Kernel & How to upgrade Kernel Version

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    Great answer, but it's not possible to get to a Terminal if we can't load Ubuntu in the first place. Loading from a LiveCD causes the error at startup. It is not possible to open a terminal.
    – nbm
    Jun 4, 2014 at 21:31

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