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    Saturday, February 15, 2014

    Fix "RHEL: Kernel will not boot, system freeze at 'starting udev'"

    Error:
    Linux machine does not boots and gets stucked at udev prompt

    Explanation
    This is a known bug in Red Hat. Please follow the belw link to reach out the bug details
    Bug 645940 - Kernel will not boot, just sits at 'starting udev'

    Clocksource is the name of the new time keeping subsystem introduced in linux 2.6 kernel. In the subsystem there are several clock sources that can be used to read the time. One of them is the tsc clocksource which uses the time stamp counter that is present on each processor and can be used to track how much time has elapsed. The TSCs on the different processor are not necessarily perfectly in sync with each other so time can appear to go backward if the TSC is read on one processor and then another processor. Early version of the TScs clock source did not handle this case, which can be lead to the guest operating system not responding. Due to the different timing behavior of running in a virtual machine this can be observed more frequently.



    Solution
    Append clocksource=acpi_pm in your grub.conf file with the kernel entry as shown in below screenshots


    Follow the screenshots


    Press the 'e' button to goto the edit option


    Go to the kernel option and again press 'e' and add the following at the end of the line
    clocksource=acpi_pm


    Press enter to save and hit 'b' to boot your machine.

    Make sure to add this entry in your grub.conf file to avoid future issues in the machine
    # vi /etc/grub.conf
    default=0
    timeout=5
    splashimage=(hd0,0)/grub/splash.xpm.gz
    hiddenmenu
    title CentOS Linux Server (2.6.18-238.el5PAE)
        root (hd0,0)
        kernel /vmlinuz-2.6.18-238.el5PAE ro root=LABEL=/ rhgb quiet 
    clocksource=acpi_pm
        initrd /initrd-2.6.18-238.el5PAE.img


    Follow the below links for more tutorials

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