DESK-XZ7-L/Deployment/Standalone boot

History
ID#	Issue Date	Notes
17xxx	Q1 2023	DESK-XZ7-L 1.0.0 release

Standalone boot

Introduction

This document was written and tested with the software/hardware combination described in the history table above. However, it contains general concepts that can be adapted to any DAVE Embedded Systems' Linux platform.

The following programming examples are intended for laboratory usage or for preliminary deployment strategy. A complete deployment strategy has to be carefully identifiyed taking into account the overall arguments like: boot speed, safe boot, recovery mechanisms, watchdog supervisor, etc.

We'll explain how to program and configure a <SOM> to boot in standalone mode, without the need for a system microSD card or an NFS server, with three options:

• booting with SD only
  • in this configuration the whole system will boot without the need for a NOR/NAND flashes storage, all images and the root file system will be fetched from the SD card
• booting with NOR and NAND internal storage
  • in this configuration the primary boot images will be fetched from NOR flash storage, while the root file system will be fetched from NAND flash

Program boot images into SD card

The SD card should have at least 2 partition:

• the first must be an FAT32 partition (type b) with size of at least 64MB
• the second is a normal linux partition (type 83) of at least 512M with ext3/ext4 filesystem

Create the SD card partitions

• SD device has to be partitioned and properly formatted choosing the file system for each partition
• an example of SD partitioning script is the following one:

#!/bin/sh

node=$1

# partition size in MB
RESERVED=8
BOOT_ROM_SIZE=128
RFS_SIZE=2048

# create the SDCARD partition
part=""
echo ${node} | grep mmcblk > /dev/null
if [ "$?" -eq "0" ]; then
        part="p"
fi

# print the SD total capacity
total_size=`sfdisk -s ${node}`
total_size=`expr ${total_size} / 1024`
echo SD total size: ${total_size}KB

# calculate partition sizes
boot_start=`expr ${RESERVED} \\* 1024 \\* 1024 / 512`
boot_size=`expr ${BOOT_ROM_SIZE} \\* 1024 \\* 1024 / 512`
rfs_start=`expr ${boot_size} + ${boot_start}`
rfs_size=`expr ${RFS_SIZE} \\* 1024 \\* 1024 / 512`

umount ${node}${part}1 > /dev/null 2>&1
umount ${node}${part}2 > /dev/null 2>&1

# call sfdisk to create partition table
{ echo ${boot_start},${boot_size},0c,-; echo ${rfs_start},${rfs_size},83,-; } | sfdisk --force ${node}

# format the SDCARD partition
echo "formatting boot"
mkfs.vfat -F 32 -n BOOT  ${node}${part}1
echo "formatting rfs"
mkfs.ext4 -F ${node}${part}2 -Lrfs

E.g.

vdk@vagrant:~/desk-xz-l$ sudo ./sdcard-partition.sh /dev/sdc
SD total size: 7580KB
Checking that no-one is using this disk right now ... OK

Disk /dev/sdc: 7.41 GiB, 7948206080 bytes, 15523840 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: 0xd775a452

Old situation:

Device     Boot Start      End  Sectors  Size Id Type
/dev/sdc1        8192 15523839 15515648  7.4G  b W95 FAT32

>>> Created a new DOS disklabel with disk identifier 0x3f242b9b.
/dev/sdc1: Created a new partition 1 of type 'W95 FAT32 (LBA)' and of size 128 MiB.
/dev/sdc2: Created a new partition 2 of type 'Linux' and of size 2 GiB.
Partition #2 contains a ext4 signature.
/dev/sdc3: Done.

New situation:
Disklabel type: dos
Disk identifier: 0x3f242b9b

Device     Boot  Start     End Sectors  Size Id Type
/dev/sdc1        16384  278527  262144  128M  c W95 FAT32 (LBA)
/dev/sdc2       278528 4472831 4194304    2G 83 Linux

The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
formatting boot
mkfs.fat 4.1 (2017-01-24)
formatting rfs
mke2fs 1.45.5 (07-Jan-2020)
/dev/sdc2 contains a ext4 file system labelled 'rfs'
        created on Mon Nov 21 13:14:20 2022
Creating filesystem with 524288 4k blocks and 131072 inodes
Filesystem UUID: cc691ca0-1eb4-4ff9-87cc-da74f9e91685
Superblock backups stored on blocks: 
        32768, 98304, 163840, 229376, 294912

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

dvdk@vagrant:~/desk-xz-l$ 

Then, insert the SD card in the target and boot the system via SD or NFS as described in the e [[(<KIT>)#Quick_start_guide|Quick start guide]]

• create a mount point and mount the first partition

root@bora:~# mkdir -p /mnt/sd
root@bora:~# mount /dev/mmcblk0p1 /mnt/sd

• copy boot image files

root@bora:~# cp BOOT.BIN /mnt/sd
root@bora:~# cp image.ub /mnt/sd
root@bora:~# cp boot.scr /mnt/sd

Program root file system into SD card

Now, you can extract the root file system into that directory

• mount the ext3/ext4 volume in the temporary directory

root@bora:~# mount /dev/mmcblk0p2 /mnt/sd
[ 1810.899327] EXT4-fs (mmcblk2p2): mounted filesystem with ordered data mode. Opts: (null)
root@bora:~#

root@bora:~# tar xf images/linux/rootfs.tar.gz -C /mnt/sd

• finally, you need to cleanly umount and safely reboot or turn off the system.

root@bora:~# umount /mnt/sd
root@bora:~# reboot

Reboot the system and configure U-Boot to apply the new configuration

=> setenv bootcmd run mmcboot
=> saveenv

Program boot images into internal storage

Program the NOR flash

u-Boot

Update to the latest u-boot version allows usage of u-boot environment variables available.

=> run load

fit image

We assume that the following environment variables are present in u-boot:

loadk=tftpboot ${loadaddr} ${serverip}:${bootfile}
loadfdt=tftpboot ${fdtaddr} ${serverip}:${fdtfile}
spi_updatek=sf erase 200000 800000; sf write ${loadaddr} 200000 ${filesize}
spi_updatefdt=sf erase 180000 80000; sf write ${fdtaddr} 180000 ${filesize}
spi_loadk=sf read ${loadaddr} 200000 800000
spi_loadfdt=sf read ${fdtaddr} 180000 80000
spi_nand=sf probe; run spi_loadk spi_loadfdt nandargs addcons addmisc; if run configid_fixupfdt; then bootm ${loadaddr} - ${fdtaddr}; fi

• Update the bootfile and fdtfile environment variables to fit the filename as found inside the TFTP server.
• Program kernel and device tree on NOR flash with the following U-Boot command

sf probe; run loadk spi_updatek loadfdt spi_updatefdt

E.g.:

=> sf probe; run loadk spi_updatek loadfdt spi_updatefdt

Reboot the system and configure U-Boot to apply the new configuration

=> setenv bootcmd run spi_nand
=> saveenv

Program root file system into NAND flash

• Boot the system via SD or NFS as described in the e [[(<KIT>)#Quick_start_guide|Quick start guide]]
• By default, the NAND is already partitioned to allow booting from NAND-only (see next section) and, thus, some partitions are reserved for u-boot and kernel images. Here we won't modify this default configuration. The MTD partitions can be dumped with /proc/mtd (the partition's name should be self-explanatory)

Please note that MTD partition index may change depending of flash device availability, flash device size, u-boot environment variables or kernel device driver load order. Always take care of looking inside /proc/mtd to match your specific layout

• Format and initialize nand-ubi partition, which in our case is mtd7, using UBI with:

ubiformat /dev/mtd0
ubiattach -m 0
ubimkvol /dev/ubi0 -N rootfs -m

E.g.

root@bora:~# ubiformat /dev/mtd0

• Now mount the UBI volume using UBIFS in a temporary directory

mkdir -p /mnt/nand
mount -t ubifs ubi0_0 /mnt/nand

E.g.:

root@bora:~# mkdir -p /mnt/nand
root@bora:~# mount -t ubifs ubi0_0 /mnt/nand

• you can now extract the root file system into that directory

tar xvjf -C /mnt/nand

• finally, you need to cleanly umount and detach the MTD partition

umount /mnt/nand/
ubidetach -m 0

E.g.

root@bora:~# umount /mnt/nand/
[ 2446.743091] UBIFS: un-mount UBI device 0, volume 0
[ 2446.749670] UBIFS: background thread "ubifs_bgt0_0" stops
root@bora:~# ubidetach -m 
[ 2450.738153] UBI: detaching mtd7 from ubi0
[ 2450.759527] UBI: mtd7 is detached from ubi0

You can now safely reboot or turn off the system.

In U-Boot environment check the following variable, which must contain the same MTD partition number used above

nand_args=setenv bootargs root=ubi0:rootfs rootfstype=ubifs rw ubi.mtd=0

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