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Thread: Fat32, UEFI, Reserved BIOS boot area?

  1. #31
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    Re: Fat32, UEFI, Reserved BIOS boot area?

    Using GParted I deleted all partitions. I booted a Flash drive with Ubuntu 20 on it. I selected "erase everything and reinstall". I now seem to have a working laptop.
    The installer created
    /dev/sda1, fat32, /boot/efi, 512 MB
    /dev/sda2, extended, 900GB
    ... /dev/sda5, ext4, 900GB

    When restarting the laptop I first went to boot menu and selected legacy boot.

    I wonder what will happen if I don't go to Boot Menu / Legacy Boot first. I'm a bit scared to try.

    This whole UEFI vs old BIOS thing is horrible. It screws me up. It is not like I learn this because my job requires me to partition laptops all the time. I run into this once every few years when I partition / install Ubuntu for myself or a family member. When my systems work as they should there is no reason for me to know anything about legacy BIOS versus new-fangled UEFI.
    Last edited by webmanoffesto; April 5th, 2021 at 07:54 PM.

  2. #32
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    Re: Fat32, UEFI, Reserved BIOS boot area?

    Quote Originally Posted by webmanoffesto View Post
    When restarting the laptop I first went to boot menu and selected legacy boot.
    Why on Earth would you do such a thing?

    Quote Originally Posted by CatKiller View Post
    Use UEFI or use Legacy. Don't mix and match, it won't work.

  3. #33
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    Ubuntu 20.04 Focal Fossa

    Re: Fat32, UEFI, Reserved BIOS boot area?

    Quote Originally Posted by webmanoffesto View Post
    Using GParted I deleted all partitions. I booted a Flash drive with Ubuntu 20 on it. I selected "erase everything and reinstall". I now seem to have a working laptop.
    The installer created
    /dev/sda1, fat32, /boot/efi, 512 MB
    /dev/sda2, extended, 900GB
    ... /dev/sda5, ext4, 900GB

    When restarting the laptop I first went to boot menu and selected legacy boot.

    I wonder what will happen if I don't go to Boot Menu / Legacy Boot first. I'm a bit scared to try.

    This whole UEFI vs old BIOS thing is horrible. It screws me up. It is not like I learn this because my job requires me to partition laptops all the time. I run into this once every few years when I partition / install Ubuntu for myself or a family member.
    Two primary partitions and then sda5 together with an ESP identified as sda1.

    I can't see how the installer would do this as a fresh installation?

    This is a old-style MBR partition scheme with a new EFI partition - very unusual..............

    Can you post the output in code tags
    Code:
    sudo parted -l

  4. #34
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    Re: Fat32, UEFI, Reserved BIOS boot area?

    Two primary partitions and then sda5 together with an ESP identified as sda1. I can't see how the installer would do this as a fresh installation?
    Strange but true. Do a BIOS mode install, choose "Erase Disk and Install" and this is the result. Here's a confirming case from a VM install of Ubuntu 20.04:
    Code:
    Disk /dev/vda: 21.5GB
    Sector size (logical/physical): 512B/512B
    Partition Table: msdos
    Disk Flags: 
    
    Number  Start   End     Size    Type      File system  Flags
     1      1049kB  538MB   537MB   primary   fat32        boot
     2      539MB   21.5GB  20.9GB  extended
     5      539MB   21.5GB  20.9GB  logical   ext4

  5. #35
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    May 2010
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    Re: Fat32, UEFI, Reserved BIOS boot area?

    Quote Originally Posted by CatKiller View Post
    Why on Earth would you do such a thing?
    Do you mean why would I boot using bios boot?
    I had already turned off secure boot. And now when I selected bios boot. I think those two match.
    How that fits into how the Ubuntu installer and the fat32 /boot/efi partition, I don't know.

    Would it be more correct to do UEFI boot or legacy BIOS boot now?
    Last edited by webmanoffesto; April 5th, 2021 at 07:43 PM.

  6. #36
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    Re: Fat32, UEFI, Reserved BIOS boot area?

    Quote Originally Posted by tea for one View Post
    Two primary partitions and then sda5 together with an ESP identified as sda1. I can't see how the installer would do this as a fresh installation? This is a old-style MBR partition scheme with a new EFI partition - very unusual. Can you post the output in code tags "sudo parted -l"
    Here's the output
    Code:
    Model: ATA Samsung SSD 850 (scsi)
    Disk /dev/sda: 1000GB
    Sector size (logical/physical): 512B/512B
    Partition Table: msdos
    Disk Flags: 
    
    Number  Start   End     Size    Type      File system  Flags
     1      1049kB  538MB   537MB   primary   fat32        boot
     2      539MB   1000GB  1000GB  extended
     5      539MB   1000GB  1000GB  logical   ext4
    
    sudo fdisk -l
    Disk /dev/loop0: 55.48 MiB, 58159104 bytes, 113592 sectors
    Units: sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    
    Disk /dev/sda: 931.53 GiB, 1000204886016 bytes, 1953525168 sectors
    Disk model: Samsung SSD 850 
    Units: sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disklabel type: dos
    Disk identifier: 0xdd28ceae
    
    Device     Boot   Start        End    Sectors  Size Id Type
    /dev/sda1  *       2048    1050623    1048576  512M  b W95 FAT32
    /dev/sda2       1052670 1953523711 1952471042  931G  5 Extended
    /dev/sda5       1052672 1953523711 1952471040  931G 83 Linux
    
    Disk /dev/loop8: 138.84 MiB, 145563648 bytes, 284304 sectors
    Units: sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Last edited by webmanoffesto; April 5th, 2021 at 07:51 PM.

  7. #37
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    May 2008
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    Re: Fat32, UEFI, Reserved BIOS boot area?

    Both examples from Dennis N and webmanoffesto have certainly surprised me.

    I assume that this is a result of using a msdos partition table?

    It would indicate that the current Ubuntu installer creates unexpected results (other than the usual problem of ignoring the user choice of grub destination).

    Moreover, it would be relevant to encourage the use of gpt (partition scheme) and UEFI mode installations to try and avoid this unusual result.

  8. #38
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    Xubuntu 20.04 Focal Fossa

    Re: Fat32, UEFI, Reserved BIOS boot area?

    At the risk of overcomplicating the situation which has totally baffled you I suspect you may do better to trash everything so far and start again completely clean. Make sure that the computer is setup to use UEFI, not legacy or CSM and also ensure Secure boot is disabled in the UEFI setup.
    I suggest then using gparted on a live OS booted in UEFI mode to firstly create a new GPT partition table on the hard disk of the computer but not bother about creating any partitions.

    Now boot to your live install USB in UEFI mode and let that carry out a default installation using the whole hard disk. The installer will then create all the needed partitions for you and you will not have to bother about the details.

    You will end up with a small (~200 - 500M) fat32 ESP/EFI partition, and a large ext4 partition for / (root) with everything else needed included in it. It is essential that you boot the live USB in UEFI mode to do this.

  9. #39
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    Re: Fat32, UEFI, Reserved BIOS boot area?

    Quote Originally Posted by ajgreeny View Post
    At the risk of overcomplicating the situation
    I would be willing to try that. Do you think I could also use GParted to create the boot partition, the / root and the /home partitions?
    How would I do that?

  10. #40
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    Re: Fat32, UEFI, Reserved BIOS boot area?

    Boot a live session in UEFI mode
    Use gparted to only create a gpt partition table

    Then let the installer automatically create the partitions.

    ajgreeny already mentioned this.

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