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SChen.11
Visitor II
April 15, 2020
Question

The gpt partition table dmaged

  • April 15, 2020
  • 1 reply
  • 1569 views

Hi, I read more wiki pages and found below command to partition emmc on uboot

setenv emmc_part "name=ssbl,size=2MiB;name=bootfs,type=linux,bootable,size=64MiB;name=rootfs,type=linux,size=512"
gpt write mmc 1 ${emmc_part}

When my board start up and execute above commands. I use gdisk to saw some error message.

gdisk -l /dev/mmcblk1
GPT fdisk (gdisk) version 1.0.1
 
Caution: invalid backup GPT header, but valid main header; regenerating
backup header from main header.
 
Warning! One or more CRCs don't match. You should repair the disk!
 
Partition table scan:
 MBR: protective
 BSD: not present
 APM: not present
 GPT: damaged
 
****************************************************************************
Caution: Found protective or hybrid MBR and corrupt GPT. Using GPT, but disk
verification and recovery are STRONGLY recommended.
****************************************************************************
Disk /dev/mmcblk1: 7733248 sectors, 3.7 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 00042021-0408-4601-9DCC-A8C51255994F
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 7733214
Partitions will be aligned on 2-sector boundaries
Total free space is 7598012 sectors (3.6 GiB)
 
Number Start (sector) End (sector) Size Code Name
 1 34 4129 2.0 MiB 0700 ssbl
 2 4130 135201 64.0 MiB 8300 bootfs
 3 135202 135202 512 bytes 8300 rootfs

So, I am confused about this. The GPT shows damaged.

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    1 reply

    C
    Christophe Guibout
    ST Employee
    May 29, 2020

    Hi @Community member​ ,

    I see two potential issues :

    - the backup GPT is not placed where it should be (offset issue), in that case, before creating new GPT table, erase it before :

    sgdisk -o -Z /dev/mmcblk1

    - The size of rootfs partition seems to be a bit small (512 bytes), maybe 512 MiB would be better.

    Anyway, I tried to reproduice it on my side by modifying the GPT table in u-boot, and check if modifications are taken into account without any error on backup GPT table:

    1) Check that everything is fine (initial conditions)

    root@stm32mp1:~# gdisk -l /dev/mmcblk0
GPT fdisk (gdisk) version 1.0.4
 
Partition table scan:
 MBR: protective
 BSD: not present
 APM: not present
 GPT: present
 
Found valid GPT with protective MBR; using GPT.
Disk /dev/mmcblk0: 31116288 sectors, 14.8 GiB
Sector size (logical/physical): 512/512 bytes
Disk identifier (GUID): 97C3E279-9EC4-4D8C-9DBA-20F3D3C3B81D
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 3145694
Partitions will be aligned on 2-sector boundaries
Total free space is 0 sectors (0 bytes)
 
Number Start (sector) End (sector) Size Code Name
 1 34 545 256.0 KiB 8301 fsbl1
 2 546 1057 256.0 KiB 8301 fsbl2
 3 1058 5153 2.0 MiB 8301 ssbl
 4 5154 136225 64.0 MiB 8300 bootfs
 5 136226 168993 16.0 MiB 8300 vendorfs
 6 168994 1705857 750.4 MiB 8300 rootfs
 7 1705858 3145694 703.0 MiB 8300 userfs

    2) Update GPT table in u-boot (increase rootfs partition size)

    mmc dev 0
setenv emmc_part "name=fsbl1,size=256KiB;name=fsbl2,size=256KiB;name=ssbl,size=2MiB;name=bootfs,type=linux,bootable,size=64MiB;name=vendorfs,type=linux,size=16MiB;name=rootfs,type=linux,size=768MiB;name=userfs,type=linux,size=600MiB"
gpt write mmc 0 ${emmc_part}

    3) Check is modification are OK without any error :

    root@stm32mp1:~# gdisk -l /dev/mmcblk0
GPT fdisk (gdisk) version 1.0.4
 
Partition table scan:
 MBR: protective
 BSD: not present
 APM: not present
 GPT: present
 
Found valid GPT with protective MBR; using GPT.
Disk /dev/mmcblk0: 31116288 sectors, 14.8 GiB
Sector size (logical/physical): 512/512 bytes
Disk identifier (GUID): 54B02E87-0600-4775-B5D0-5621F9B65990
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 31116254
Partitions will be aligned on 2-sector boundaries
Total free space is 28145597 sectors (13.4 GiB)
Number Start (sector) End (sector) Size Code Name
 1 34 545 256.0 KiB 0700 fsbl1
 2 546 1057 256.0 KiB 0700 fsbl2
 3 1058 5153 2.0 MiB 0700 ssbl
 4 5154 136225 64.0 MiB 8300 bootfs
 5 136226 168993 16.0 MiB 8300 vendorfs
 6 168994 1741857 768.0 MiB 8300 rootfs
 7 1741858 2970657 600.0 MiB 8300 userfs

    GPT update is taken into account and no backup GPT issue. Of course, in that case, userfs partition needs to be formated to be usable.

    If it doesn't help, please dump your GPT table in order to look into.

    BR,

    Christophe

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