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Use the fdisk utility to prepare the SD card on a Linux host.

As all operations are made with the root permissions, be careful, and verify the destination /dev/sdX to avoid corruption of the system drives:

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$ sudo fdisk /dev/sdx

Welcome to fdisk (util-linux 2.37.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Command (m for help): p
Disk /dev/sdb: 7,39 GiB, 7932477440 bytes, 15493120 sectors
Disk model: STORAGE DEVICE
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: 0xc36d1c99

Device     Boot  Start      End  Sectors  Size Id Type
/dev/sdb1         2048   196607   194560   95M  b W95 FAT32
/dev/sdb2       196608 15493119 15296512  7,3G 83 Linux

Remove all partitions using the d command:

Code Block

Command (m for help): d
Partition number (1,2, default 2):

Partition 2 has been deleted.

Command (m for help): d
Selected partition 1
Partition 1 has been deleted.

Command (m for help): p
Disk /dev/sdb: 7,39 GiB, 7932477440 bytes, 15493120 sectors
Disk model: STORAGE DEVICE
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: 0xc36d1c99

Use the n command to create new primary (p) partitions. The first partition size is 100M, the second one size is all free space left on SD card:

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Command (m for help): n
Partition type
   p   primary (0 primary, 0 extended, 4 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1):
First sector (2048-15493119, default 2048):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-15493119, 
default 15493119): +100M

Created a new partition 1 of type 'Linux' and of size 100 MiB.
Partition #1 contains a vfat signature.

Do you want to remove the signature? [Y]es/[N]o: Y

The signature will be removed by a write command.

Command (m for help): t
Selected partition 1
Hex code or alias (type L to list all): b
Changed type of partition 'Linux' to 'W95 FAT32'.

Command (m for help): n
Partition type
   p   primary (1 primary, 0 extended, 3 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (2-4, default 2):
First sector (206848-15493119, default 206848):
Last sector, +/-sectors or +/-size{K,M,G,T,P} 
(206848-15493119, default 15493119):

Created a new partition 2 of type 'Linux' and of size 7,3 GiB.

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
$

Install U-Boot to the beginning of the SD card (the prebuilt U-Boot SPL and TPL images can be obtained from the Emcraft web site):
Code Block
$ sudo dd if=SPL of=/dev/sdb bs=1k seek=1 conv=notrunc; sync $ sudo dd if=u-boot.img of=/dev/sdb bs=1k seek=128 conv=notrunc; sync
Format the Boot boot partition with a FAT file system:
Code Block
$ sudo mkfs.vfat /dev/sdb1 mkfs.fat 4.2 (2021-01-31) $

Install the Linux bootable image to the Boot partition on the SD card:

Code Block
$ sudo mount /dev/sdb1 /mnt $ sudo cp ${INSTALL_ROOT}/projects/rootfs/roofts.uImage /mnt $ sudo umount /mnt

Format the RootFS partition with the EXT4 file system:

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$ sudo mkfs.ext4 -E lazy_itable_init=0,lazy_journal_init=0 /dev/sdb2
mke2fs 1.46.5 (30-Dec-2021)
Creating filesystem with 1910784 4k blocks and 478608 inodes
Filesystem UUID: ba548d3d-f65e-4353-a08b-d6bc711922a9
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632

Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done
$

The lazy_itable_init=0,lazy_journal_init=0 options to mkfs.ext4 are required to disable "lazy initialization", due to issues with this EXT4 feature on the no-MMU targets in kernel 5.15.

Mount the RootFS rootfs partition, change to the mounted partition directory and unpack the rootfs.tar.gz image here (the command can require the root privileges):
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$ sudo mount /dev/sdb2 /mnt $ cd /mnt $ sudo tar zxf ${INSTALL_ROOT}/projects/rootfs/rootfs.tar.gz $ cd - $ sudo umount /mnt
Set up the boot jumper on the target board to boot from SD Card.
Insert the prepared card into the SD Card holder on the target.

Update the bootargs environment variable in U-boot to tell the kernel to mount the root file system from the dedicated partition on the SD Card. For this, power on the target board and stop booting in the U-Boot command monitor by pressing any key:

Code Block

U-Boot SPL 2023.04 (Dec 12 2023 - 13:24:53 +0000)
Trying to boot from MMC1


U-Boot 2023.04 (Dec 12 2023 - 13:24:53 +0000)

Model: NXP imxrt1170-evk board
DRAM:  960 KiB (effective 64.9 MiB)
Core:  72 devices, 15 uclasses, devicetree: separate
MMC:   FSL_SDHC: 0
Loading Environment from MMC... OK
In:    serial@4007c000
Out:   serial@4007c000
Err:   serial@4007c000
Net:   eth0: ethernet@40424000
Hit any key to stop autoboot:  0
=>

Update the bootargs environment variable to use /dev/mmcblk0p2 matching the 2nd partition on the SD Card:

Code Block
=> setenv bootargs root=/dev/mmcblk0p2 rw rootwait => saveenv Saving Environment to MMC... Writing to MMC(0)... OK =>

Reset the board to boot Linux with the root filesystem on the SD Card. Wait for the shell prompt and check that the system is booted and the mount utility shows that the root file system resides on the SD Card partition /dev/mmcblb0p2:

Code Block

U-Boot SPL 2023.04 (Dec 12 2023 - 13:24:53 +0000)
Trying to boot from MMC1


U-Boot 2023.04 (Dec 12 2023 - 13:24:53 +0000)

Model: NXP imxrt1170-evk board
DRAM:  960 KiB (effective 64.9 MiB)
Core:  72 devices, 15 uclasses, devicetree: separate
MMC:   FSL_SDHC: 0
Loading Environment from MMC... OK
In:    serial@4007c000
Out:   serial@4007c000
Err:   serial@4007c000
Net:   eth0: ethernet@40424000
Hit any key to stop autoboot:  0
4984553 bytes read in 427 ms (11.1 MiB/s)
## Booting kernel from Legacy Image at 80007fc0 ...
   Image Name:   Linux-6.1.22
   Image Type:   ARM Linux Multi-File Image (uncompressed)
   Data Size:    4984489 Bytes = 4.8 MiB
   Load Address: 80008000
   Entry Point:  80008001
   Contents:
      Image 0: 4972544 Bytes = 4.7 MiB
      Image 1: 11933 Bytes = 11.7 KiB
   Verifying Checksum ... OK
## Flattened Device Tree from multi component Image at 80007FC0
   Booting using the fdt at 0x804c600c
Working FDT set to 804c600c
   Loading Multi-File Image
   Loading Device Tree to 2032a000, end 2032fe9c ... OK
Working FDT set to 2032a000

Starting kernel ...

Booting Linux on physical CPU 0x0
Linux version 6.1.22 (sasha@workbench.emcraft.com) (arm-none-eabi-gcc 
(GNU Arm Embedded Toolchain 10.3-2021.10) 10.3.1 20210824 (release), GNU ld 
(GNU Arm Embedded Toolchain 10.3-2021.10) 2.36.1.20210621) #207 Tue Dec 12 
12:30:27 UTC 2023
...
mmc0: new high speed SDHC card at address 59b4
mmcblk0: mmc0:59b4 USD   7.39 GiB
 mmcblk0: p1 p2
EXT4-fs (mmcblk0p2): recovery complete
EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. 
Quota mode: disabled.
VFS: Mounted root (ext4 filesystem) on device 179:2.
devtmpfs: mounted
Freeing unused kernel image (initmem) memory: 92K
This architecture does not have kernel memory protection.
Run /sbin/init as init process
[80] Jan 01 00:00:02 Running in background
/ # RTL8201F Fast Ethernet 40424000.ethernet-1:00: attached PHY driver 
(mii_bus:phy_addr=40424000.ethernet-1:00, irq=POLL)
fec 40424000.ethernet eth0: Link is Up - 100Mbps/Full - flow control off
random: crng init done
/ # echo Hello
Hello
/ # mount
/dev/root on / type ext4 (rw,relatime)
devtmpfs on /dev type devtmpfs (rw,relatime)
proc on /proc type proc (rw,relatime)
sysfs on /sys type sysfs (rw,relatime)
devpts on /dev/pts type devpts (rw,relatime,gid=5,mode=620,ptmxmode=000)
/ # dmesg | grep "Mounted root"
VFS: Mounted root (ext4 filesystem) on device 179:2.
/ # ls -l /dev/mmcblk0p2 
brw-------    1 root     root      179,   2 Jan  1 00:00 /dev/mmcblk0p2
/ #

Boot the board with the root file system on the SD Card. Wait for the shell prompt and check that root file system is mounted in the Read/Write mode:

Code Block

...
Run /sbin/init as init process
[80] Jan 01 00:00:01 Running in background
/ # RTL8201F Fast Ethernet 40424000.ethernet-1:00: 
attached PHY driver (mii_bus:phy_addr=40424000.ethernet-1:00, irq=POLL)
random: crng init done

/ # cp /bin/busybox /root/
/ # reboot
The system is going down NOW!
Sent SIGTERM to all processes
[80] Jan 01 00:11:54 Early exit: Terminated by signal
Terminated
Requesting system reboot
reboot: Restarting system

U-Boot SPL 2023.04 (Dec 12 2023 - 13:24:53 +0000)
Trying to boot from MMC1
...
/ # md5sum /bin/busybox /root/busybox
fc95be9f30c93e98beda14b2ec2c818f  /bin/busybox
fc95be9f30c93e98beda14b2ec2c818f  /root/busybox
/ #

Version	Old Version 3	New Version Current
Changes made by	Natalia Sofronova	Natalia Sofronova
Saved on	Jun 25, 2024	Apr 23, 2025

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