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Thread: Booteable USB for Legacy and UEFI

  1. #1
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    Question Booteable USB for Legacy and UEFI

    Hello dear friends,

    Following a tutorial, I created a booteable USB for Ubuntu. From an Ubuntu system I created in the USB the following partitions



    Then I installed Ubuntu into the LUKS Partition. So far so good.

    My concern is that, acording to the tutorial, the USB should boot in UEFI or Legacy computers but it only boot on UEFI. On Legacy it shows the typic black screen with white line flickering.

    Somebody can tell me what should I do?

    Thank you so much in advance
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  2. #2
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    Re: Booteable USB for Legacy and UEFI

    How about giving us a link to that tutorial?

    Regards
    It is a machine. It is more stupid than we are. It will not stop us from doing stupid things.
    Ubuntu user #33,200. Linux user #530,530


  3. #3
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    Re: Booteable USB for Legacy and UEFI

    Quote Originally Posted by grahammechanical View Post
    How about giving us a link to that tutorial?

    Regards
    I checked the tutorial in Reddit. If it's 0k to paste the URL in this forum I can do it. I didn't do it because I thought it was not allowed

  4. #4
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    Re: Booteable USB for Legacy and UEFI

    This is the link I often provide for burning a Ubuntu ISO image to USB memory stick.

    https://ubuntu.com/tutorials/create-...ntu#1-overview

    In the reply to thread box click the icon of the planet and a link of a chain. And post the web site address in the panel that appears.

    I asked for the link to the tutorial because I wondered why you were doing things that why. Usually a person downloads and burns the standard ISO image to USB memory stick. Then if we load the USB stick in UEFI mode Ubuntu will install in UEFI mode. And if we load the USB stick in Legacy mode Ubuntu will install in legacy mode. I do not know of any reason to partition the USB stick the way you have done.

    Regards
    It is a machine. It is more stupid than we are. It will not stop us from doing stupid things.
    Ubuntu user #33,200. Linux user #530,530


  5. #5
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    Re: Booteable USB for Legacy and UEFI

    In your initial post, you indicate that you "installed" Ubuntu to the LUKS partition. I take that to mean that you have an actual install of Ubuntu on the flash drive and that this is not a USB meant to be used to install Ubuntu, is that correct?

    Could you post the link you used to do this to help clarify things for us? If you do have an actual install of Ubuntu on the flash drive and want to boot it on UEFI computers and Legacy computers, you will need a bios_grub partition (unformated) on the flash drive as well as an i386-pc directory in the /boot/grub partition and need to install Grub in legacy mode. An example of this is posted below. You will need to change the --boot-directory path shown below to suit your system as well as the device if it is not /dev/sdb

    grub-install --target=i386-pc --recheck --boot-directory=/mnt/seagate/boot /dev/sdb
    The command above needs the i386-pc directory in the /boot/grub directory on the flash drive. If you do not have it there, copy it from the /usr/lib/grub/ directory from any Ubuntu or Linux install.

  6. #6
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    Re: Booteable USB for Legacy and UEFI

    Quote Originally Posted by yancek View Post
    In your initial post, you indicate that you "installed" Ubuntu to the LUKS partition. I take that to mean that you have an actual install of Ubuntu on the flash drive and that this is not a USB meant to be used to install Ubuntu, is that correct?

    Could you post the link you used to do this to help clarify things for us? If you do have an actual install of Ubuntu on the flash drive and want to boot it on UEFI computers and Legacy computers, you will need a bios_grub partition (unformated) on the flash drive as well as an i386-pc directory in the /boot/grub partition and need to install Grub in legacy mode. An example of this is posted below. You will need to change the --boot-directory path shown below to suit your system as well as the device if it is not /dev/sdb



    The command above needs the i386-pc directory in the /boot/grub directory on the flash drive. If you do not have it there, copy it from the /usr/lib/grub/ directory from any Ubuntu or Linux install.
    I followed this tutorial although it boot perfect in UEFI, it doesn't boot in Legacy as I said.

    To clarify the process I made. I installed a Live Ubuntu in USB#1 with Rufus, then I booted from this USB, I connected USB#2, created the partitions with GParted and then I installed Ubuntu into USB#2 using the normal installer that is in the Desktop

    What I pretend is to have an "On-the-go Ubuntu" USB with an encrypted LUKS partition for my personal data, that I can boot both in UEFI and Legacy
    Last edited by santy4tas; October 18th, 2021 at 05:51 PM.

  7. #7
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    Re: Booteable USB for Legacy and UEFI

    The following links show ways that work to create an installed Ubuntu system, that can boot both in UEFI mode and BISO mode (alias CSM alias legacy mode).

    - How to Create a Full Install of Ubuntu 20.04 to USB Device Step by Step

    - Installation/UEFI-and-BIOS


    Maybe you can use instructions in the first link to create a boot system for BIOS mode. Otherwise you can backup the personal data in the home directory and make a fresh installation.

  8. #8
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    Re: Booteable USB for Legacy and UEFI

    If you want to boot both UEFI or Legacy on different computers, you will need the bios-grub unformatted partition. I don't see anything in the link you posted that discusses booting in Legacy mode.

  9. #9
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    Re: Booteable USB for Legacy and UEFI

    Quote Originally Posted by sudodus View Post
    The following links show ways that work to create an installed Ubuntu system, that can boot both in UEFI mode and BISO mode (alias CSM alias legacy mode).

    - How to Create a Full Install of Ubuntu 20.04 to USB Device Step by Step

    - Installation/UEFI-and-BIOS


    Maybe you can use instructions in the first link to create a boot system for BIOS mode. Otherwise you can backup the personal data in the home directory and make a fresh installation.
    Thank you for your answer dear my friend. After visiting your suggestion of "How to Create a Full Install of Ubuntu 20.04 to USB Device Step by Step" I realized that at the end of the post I could found this:




    Taking into account this is what I need (full disk encryption) I followed the process exactly as it says, with no success, I had two problems.

    I could follow all the steps perfectly except for the last steps which says
    Now mount the ESP boot partition and copy ESP/EFI/ubuntu/grub/grub.cfg and overwrite ESP/boot/grub/grub.cfg
    Here appeared the first problem because the route ESP/EFI/ubuntu/grub is empty for me.

    Even so, I tried to boot the USB from both, UEFI System and BIOS System. It shows the GRUB on boot:




    The second problem is that no matter which option I select, I am getting the following error



    Any ideas on what I can do? Hope you can help me.

    Thank you
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  10. #10
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    Re: Booteable USB for Legacy and UEFI

    @santy4tas,

    I could follow all the steps perfectly except for the last steps which says

    Now mount the ESP boot partition and copy ESP/EFI/ubuntu/grub/grub.cfg and overwrite ESP/boot/grub/grub.cfg
    Here appeared the first problem because the route ESP/EFI/ubuntu/grub is empty for me.
    You must replace ESP by the actual mountpoint, where the ESP partition's file system is mounted, and if not mounted you must mount it.

    Do you know how to mount a partition with mount?

    Code:
    sudo mount <block device> <mountpoint>
    # for example
    sudo mkdir /mnt/esp
    sudo mount /dev/sda2 /mnt/esp
    Even so, I tried to boot the USB from both, UEFI System and BIOS System. It shows the GRUB on boot:
    The first screenshot shows the boot menu of a persistent live system made by mkusb. But you should boot into an installed system. Maybe your computer will boot into that system if you shut down your computer, unplug the persistent live drive and boot again.

    Otherwise, I don't think it works to apply 'full disk encryption' to a persistent live system.
    Last edited by sudodus; October 22nd, 2021 at 08:29 AM.

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