Booting into older versions after successful upgrade
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  1. #1
    Join Date
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    Linux (Fedora) Firefox 62.0

    Booting into older versions after successful upgrade

    Hi Friends,

    Two days ago, I for the very 1st time in my life used the "dnf system-upgrade" command to upgrade an existing Fedora Workstation installation to the latest one available out there. I 1st installed Fedora 25 Workstation 32 bit on an empty 500 GB extra HDD of mine and then followed the instructions given at the following URL.

    https://fedoraproject.org/wiki/DNF_system_upgrade

    I used the following commands one by one without any issues whatsoever and I was able to upgrade my system from the original Fedora 25 Workstation 32 bit to the latest Fedora 29 Workstation 32 bit. I am fully aware that Fedora 29 is yet to be released.

    Code:
    sudo dnf upgrade --refresh
    Code:
    sudo dnf install dnf-plugin-system-upgrade
    Code:
    sudo dnf system-upgrade download --refresh --releasever=xyz
    Code:
    sudo dnf system-upgrade reboot
    Each time I upgraded to the next release only ie from the original Fedora 25 Workstation 32 bit to Fedora 26 Workstation 32 bit and so on. I did not upgrade from Fedora 25 Workstation 32 bit to the latest Fedora 29 Workstation 32 bit directly.

    Now, I have many versions of Fedora from 25 to 29 on the initial boot menu, but I am not able to boot into any other versions except the latest Fedora 29 Workstation 32. What should I do to boot into each version of Fedora listed on the initial boot menu? Is it possible at all to boot into any of the older versions once the system has been upgraded?

    https://imgur.com/a/nzQG5Qg

    Thanks.
    fedoralinuxcommands.blogspot.com


    All the forces in the world are not so powerful as an idea whose time has come - Victor Hugo

  2. #2
    PabloTwo's Avatar
    PabloTwo is offline "Registered User" T-Shirt Winner
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    Re: Booting into older versions after successful upgrade

    You are mistaking some leftover kernel entries from earlier Fedora versions as being a gateway to the earlier versions. When you do a system-upgrade from Fedora release A to Fedora release B, you only have Fedora release B (the most recent) but will often still have a kernel or two leftover from the last install. It may still be possible to boot into an older kernel on a newer release (such as booting a fc27 kernel while actually running f28) but you would still be running the newer release.

    The normal default for grub2 is to keep only the 3 most recently installed kernels, which could and would include at least two kernels from the previous release(s) right after a fresh system upgrade. Why your grub is showing so many leftover kernels I can't say, possibly because you may have set the limit higher by editing the "installonly_limit=3" entry in your /etc/dnf/dnf.conf file. You also are showing a mix of PAE and non-PAE kernels, which may or may not be counted differently by grub as far as setting the limit to keep is concerned.

    These commands will confirm that you currently have only one Fedora release installed:
    Code:
    $ egrep -i "version|release" /etc/*release
    $ rpm -E %fedora
    Last edited by PabloTwo; 12th September 2018 at 05:25 PM.

  3. #3
    Join Date
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    Linux (Fedora) Chrome 69.0.3497.81

    Re: Booting into older versions after successful upgrade

    First of all, many thanks for the reply. Appreciated.

    Quote Originally Posted by PabloTwo
    You are mistaking some leftover kernel entries from earlier Fedora versions as being a gateway to the earlier versions. When you do a system-upgrade from Fedora release A to Fedora release B, you only have Fedora release B (the most recent) but will often still have a kernel or two leftover from the last install. It may still be possible to boot into an older kernel on a newer release (such as booting a fc27 kernel while actually running f28) but you would still be running the newer release.

    I thought so. But then I am a self-taught Linux guys, who runs a small local Linux group on an informal basis and this upgrade exercise was my way of showing them the wonders of Fedora. Thanks a lot for clarifying the things you did.

    It makes a lot more sense now. If you had not replied, I would have never got the concept clear in my head. I love the way seniors like yourself guide juniors like myself. Brilliant. I just love this forum.


    The normal default for grub2 is to keep only the 3 most recently installed kernels
    OK.

    "installonly_limit=3" entry in your /etc/dnf/dnf.conf file
    I never knew this before.

    These commands will confirm that you currently have only one Fedora release installed:
    Code:
    $ egrep -i "version|release" /etc/*release
    $ rpm -E %fedora
    OK. Here is the situation from another regular machine of mine running Fedora 27 Workstation 64 bit


    Code:
    [john@localhost ~]$ egrep -i "version|release" /etc/*release
    /etc/fedora-release:Fedora release 27 (Twenty Seven)
    /etc/os-release:VERSION="27 (Workstation Edition)"
    /etc/os-release:VERSION_ID=27
    /etc/os-release:REDHAT_BUGZILLA_PRODUCT_VERSION=27
    /etc/os-release:REDHAT_SUPPORT_PRODUCT_VERSION=27
    /etc/redhat-release:Fedora release 27 (Twenty Seven)
    /etc/system-release:Fedora release 27 (Twenty Seven)
    [john@localhost ~]$
    Thanks a lot for all the help so far.
    fedoralinuxcommands.blogspot.com


    All the forces in the world are not so powerful as an idea whose time has come - Victor Hugo

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