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Thread: GRUB2, UEFI, and Partition Types on OpenSuse 13.1

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    Default GRUB2, UEFI, and Partition Types on OpenSuse 13.1

    I have 2 questions:

    1. Can GRUB2 work on a UEFI system without a small FAT partition at the beginning of the drive? Can the /boot/efi directory be on an EXT4 partition (such as root), or is there a compatibility problem with EXT4? If so, is there a good article someone can link to here, explaining GRUB2's limitations?

    2. When I checked in fdisk or gdisk, it listed my EXT4 partitions as: "Microsoft basic". Is that standard behavior after a UEFI OpenSuse install? I changed the mislabeled partition types in GPT fdisk to 8300, and crossed my fingers that it wouldn't wipe out the entire partition. I first tested it on root which is a partition I don't care about losing, and it worked fine. Then I did it on home, and crossed fingers on both hands, and had no problem. GPT fdisk gives you a scary warning when you select "w", after changing the partition type.

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    Default Re: GRUB2, UEFI, and Partition Types on OpenSuse 13.1

    On Mon 27 Jan 2014 12:06:01 AM CST, pirithous wrote:


    I have 2 questions:

    1. Can GRUB2 work on a UEFI system without a small FAT partition at the
    beginning of the drive? Can the /boot/efi directory be on an EXT4
    partition (such as root), or is there a compatibility problem with EXT4?
    If so, is there a good article someone can link to here, explaining
    GRUB2's limitations?
    Hi
    The ESP must be formatted FAT, FAT 16 for booting with a Windows OS
    AFAIK (and which I always do), FAT 32 for linux and set to type
    ef00 to be recognized. It needs to be on it's own separate partition.

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  3. #3
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    Default Re: GRUB2, UEFI, and Partition Types on OpenSuse 13.1

    Quote Originally Posted by pirithous View Post
    I have 2 questions:

    1. Can GRUB2 work on a UEFI system without a small FAT partition at the beginning of the drive? Can the /boot/efi directory be on an EXT4 partition (such as root), or is there a compatibility problem with EXT4? If so, is there a good article someone can link to here, explaining GRUB2's limitations?
    It needs to be FAT -- either FAT16 or FAT32 will do. This is a requirement of the UEFI specification. The BIOS needs to be able to access the EFI partition, and that's what is used as "/boot/efi".

    Quote Originally Posted by pirithous View Post
    2. When I checked in fdisk or gdisk, it listed my EXT4 partitions as: "Microsoft basic". Is that standard behavior after a UEFI OpenSuse install? I changed the mislabeled partition types in GPT fdisk to 8300, and crossed my fingers that it wouldn't wipe out the entire partition. I first tested it on root which is a partition I don't care about losing, and it worked fine. Then I did it on home, and crossed fingers on both hands, and had no problem. GPT fdisk gives you a scary warning when you select "w", after changing the partition type.
    When you partition during install, "parted" is used for the partitioning.

    My understanding, which might be wrong, is that until recently there was no official ID for ext4 partitions. And so "parted" does not know how to flag it as "ext4", while the newer "gdisk" does. Presumably this will be corrected in future versions of "parted", though it might require Yast installer changes, too.

    In any case, my "ext4" partitions show a type code of "8300" in "gdisk", probably because I partitioned with "gdisk" before installing. In any case, linux still works if the partition is wrongly identified.

    Okay, here's the "parted" output for "/dev/sdb":
    Code:
    Number  Start   End     Size    File system  Name              Flags
     1      1049kB  525MB   524MB   fat16        EFI System        boot
     2      525MB   1050MB  524MB   ext2         Linux filesystem
     3      1050MB  119GB   118GB                Linux LVM         lvm
     4      119GB   141GB   21.5GB  ext4         Linux filesystem
     5      141GB   151GB   10.7GB               Linux swap
     6      151GB   162GB   10.7GB               Linux filesystem
    So I guess "parted" is fine with the linux types, but maybe Yast has not caught up. Or maybe "parted" is getting that information from the actual file system, rather than from the partition type ID.
    openSUSE Leap 15.3; KDE Plasma 5.18.6;

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    Default Re: GRUB2, UEFI, and Partition Types on OpenSuse 13.1

    Quote Originally Posted by malcolmlewis View Post
    The ESP must be formatted FAT, FAT 16 for booting with a Windows OS
    AFAIK (and which I always do), FAT 32 for linux and set to type
    ef00 to be recognized. It needs to be on it's own separate partition.
    Windows 8 came with the ESP formatted to FAT 32. I allowed the EFI partition on my second disk to be formatted by opensuse install, and it used FAT 16. As far as I know, either FAT 16 or FAT 32 is allowed by the UEFI specifications, and perhaps even FAT12 is permitted.
    openSUSE Leap 15.3; KDE Plasma 5.18.6;

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    Default Re: GRUB2, UEFI, and Partition Types on OpenSuse 13.1

    On 2014-01-27 02:56, nrickert wrote:
    > My understanding, which might be wrong, is that until recently there was
    > no official ID for ext4 partitions. And so "parted" does not know how
    > to flag it as "ext4", while the newer "gdisk" does. Presumably this
    > will be corrected in future versions of "parted", though it might
    > require Yast installer changes, too.


    Another guess: this will only happen for GPT partitions, not MBR partitions.

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    Default Re: GRUB2, UEFI, and Partition Types on OpenSuse 13.1

    Further to this thread, to give a simple example of actual use, here is the /etc/fstab from my Ultrabook which has Windows8 and openSUSE in a dual boot:
    Code:
    oldcpu@toshiba:~> cat /etc/fstab
    /dev/disk/by-id/ata-TOSHIBA_THNSNF256GMCS_X2SS10KZT68Y-part5 swap                 swap       defaults              0 0
    /dev/disk/by-id/ata-TOSHIBA_THNSNF256GMCS_X2SS10KZT68Y-part8 /                    ext4       noatime,acl,user_xattr,discard        1 1
    /dev/disk/by-id/ata-TOSHIBA_THNSNF256GMCS_X2SS10KZT68Y-part2 /boot/efi            vfat       umask=0002,utf8=true  0 0
    /dev/disk/by-id/ata-TOSHIBA_THNSNF256GMCS_X2SS10KZT68Y-part9 /home                ext4       defaults              1 2
    where you can see there is a vfat mounted as /boot/efi

    and here is the output of gdisk which is consistent with the above:
    Code:
    toshiba:/home/oldcpu # gdisk -l /dev/sda
    GPT fdisk (gdisk) version 0.8.7
    
    Partition table scan:
      MBR: protective
      BSD: not present
      APM: not present
      GPT: present
    
    Found valid GPT with protective MBR; using GPT.
    Disk /dev/sda: 500118192 sectors, 238.5 GiB
    Logical sector size: 512 bytes
    Disk identifier (GUID): A9B29122-31C4-11E2-AF00-E8E0B773C368
    Partition table holds up to 128 entries
    First usable sector is 34, last usable sector is 500118158
    Partitions will be aligned on 2048-sector boundaries
    Total free space is 2669 sectors (1.3 MiB)
    
    Number  Start (sector)    End (sector)  Size       Code  Name
       1            2048          923647   450.0 MiB   2700  Basic data partition
       2          923648         1456127   260.0 MiB   EF00  Basic data partition
       3         1456128         1718271   128.0 MiB   0C01  Basic data partition
       4         1718272       134838271   63.5 GiB    0700  Basic data partition
       5       134838272       147945471   6.2 GiB     8200  
       6       468746240       487534591   9.0 GiB     2700  Basic data partition
       7       487534592       500117503   6.0 GiB     8400  Basic data partition
       8       147945472       200374271   25.0 GiB    0700  
       9       200374272       468746239   128.0 GiB   0700
    where one can see that partition #2 , which is EF00, is my EFI partition. The partitions with nothing in the 'Name' column (5, 8, and 9) are the openSUSE partitions (swap, root and home). Then there is the EFI (already noted) and the remainder are associated with Windows8 and Toshiba putting in a recovery partition.

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