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 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
• 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

Program boot images into 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/mtd7
ubiattach -m 7
ubimkvol /dev/ubi0 -N rootfs -m

E.g.

root@sdvx-lite:~# 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@sdvx-lite:~# mkdir -p /mnt/nand
root@sdvx-lite:~# mount -t ubifs ubi0_0 /mnt/nand
[ 1810.301461] UBIFS: default file-system created
[ 1810.308952] UBIFS: background thread "ubifs_bgt0_0" started, PID 717
[ 1810.452274] UBIFS: mounted UBI device 0, volume 0, name "rootfs"
[ 1810.459421] UBIFS: LEB size: 126976 bytes (124 KiB), min./max. I/O unit sizes: 2048 bytes/2048 bytes
[ 1810.469398] UBIFS: FS size: 992698368 bytes (946 MiB, 7818 LEBs), journal size 33521664 bytes (31 MiB, 264 LEBs)
[ 1810.480976] UBIFS: reserved for root: 4952683 bytes (4836 KiB)
[ 1810.487210] UBIFS: media format: w4/r0 (latest is w4/r0), UUID 99D0F3C6-5955-4B30-9E2D-72202281BD30, small LPT model

• 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 7

E.g.

root@sdvx-lite:~# umount /mnt/nand/
[ 2446.743091] UBIFS: un-mount UBI device 0, volume 0
[ 2446.749670] UBIFS: background thread "ubifs_bgt0_0" stops
root@sdvx-lite:~# 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=7

Program boot images into SD card

u-Boot

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

mmc_update=mmc dev; setexpr blocks ${filesize} / 0x200; setexpr blocks ${blocks} + 1; mmc write ${loadaddr} 2 ${blocks}

Load u-boot binary form a tftp server:

=> run load
=> run mmc_update

fit image

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

mmc_loadk=fatload mmc ${mmcdev}:1 ${loadaddr} ${bootfile}
mmc_loadfdt=fatload mmc ${mmcdev}:1 ${fdtaddr} ${fdtfile}
mmc_loadsplash=fatload mmc ${mmcdev}:1 ${loadaddr} ${splashfile}; cp.b ${loadaddr} ${splashimage} ${filesize}
mmcboot=run mmcargs addcons addmisc; if run mmc_loadk; then if run mmc_loadfdt; then if run configid_fixupfdt; then bootm ${loadaddr} - ${fdtaddr}; fi; fi; fi

Using an SD card or an eMMC device assumes that bootfile, fdtfile and splashfile are stored into fist MMC device partition.

Then, u-boot uses the previous listed commands for reading the binary images and starting the linux bootstrap from the MMC part 2 (which is reserved for the root-file system storage).

The following u-boot environment variables are present for this purposes:

mmcargs=setenv bootargs root=${mmcroot}
mmcroot=/dev/mmcblk2p2 rootwait rw

boot vars

The following environment variables should be configured for u-boot properly reading the boot files from the first SD card partition, e.g.

=> setenv normalboot mmcboot
=> setenv bootfile 

then save the environment and reboot the system to apply the new configuration:

=> saveenv
Saving Environment to MMC...
Writing to MMC(2)... done
=> reset

Program root file system into SD card

• Boot the system via SD or NFS as described in the e [[(<KIT>)#Quick_start_guide|Quick start guide]]
• eMMC 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:

FAT32 partition

#!/bin/sh

node=$1

# partition size in MB
BOOTLOAD_RESERVE=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 ${BOOTLOAD_RESERVE} \\* 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.

root@sdvx-lite:~# ./sdcard-partition.sh /dev/mmcblk2
SD total size: 3776KB
[ 1341.905014]  mmcblk2: p1 p2
Checking that no-one is using this disk right now ... OK

Disk /dev/mmcblk2: 3.7 GiB, 3959422976 bytes, 7733248 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical):[ 1341.922729]  mmcblk2: p1 p2
 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xa77eb3f0

Old situation:

Device         Boot  Start     End Sectors  Size Id Type
/dev/mmcblk2p1        2048  264191  262144  128M  c W95 FAT32 (LBA)
/dev/mmcblk2p2      264192 4458495 4194304    2G 83 Linux

>>> Created a new DOS disklabel with disk identifier 0xcce0c36f.
Created a new partition 1 of type 'W95 FAT32 (LBA)' and of size 128 MiB.
/dev/mmcblk2p2: Created a new partition 2 of type 'Linux' and of size 2 GiB.
/dev/mmcblk2p3:
New situation:

Device         Boot  Start     End Sectors  Size Id Type
/dev/mmcblk2p1       16384  278527  262144  128M  c W95 FAT32 (LBA)
/dev/mmcblk2p2      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 3.0.28 (2015-05-16)
mkfs.fat: warning - lowercase labels might not work properly with DOS or Windows
formatting rfs
mke2fs 1.43-WIP (18-May-2015)
Discarding device blocks: done
Creating filesystem with 524288 4k blocks and 131072 inodes
Filesystem UUID: 9a685543-1af2-4e39-83f3-b8a32248c021
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

root@sdvx-lite:~#

• create a mount point and mount the first partition

mkdir -p /mnt/emmc
mount /dev/mmcblk2p1 /mnt/emmc

• copy boot image files

root@sdvx-lite:~# mount /dev/mmcblk0p2 /mnt/sd
root@sdvx-lite:~# cd /mnt/emmc
root@sdvx-lite:/mnt/emmc# cp /tftpboot/xxxxx .
root@sdvx-lite:/mnt/emmc# cd
root@sdvx-lite:~# umount /mnt/emmc

• now mount the EXT4 volume in the temporary directory

E.g.:

root@sdvx-lite:~# mount /dev/mmcblk2p2 /mnt/emmc
[ 1810.899327] EXT4-fs (mmcblk2p2): mounted filesystem with ordered data mode. Opts: (null)
root@sdvx-lite:~# cd /mnt/emmc
root@sdvx-lite:/mnt/emmc# 

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

tar xvjf sdvx-1.0.1_image-devel-sdvx-lite.tar.bz2

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

root@sdvx-lite:/mnt/emmc# cd
root@sdvx-lite:~# umount /mnt/emmc
root@sdvx-lite:~# reboot

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

=> setenv bootcmd run mmcboot
=> saveenv

ext4 partition

For using an ext4 partition also for boot files, it is possibile to change the formatting script:

{ echo ${boot_start},${boot_size},83,-; echo ${rfs_start},${rfs_size},83,-; } | sfdisk --force ${node}

and formatting the first partition using mkfs.ext4

mkfs.ext4 -F ${node}${part}1 -Lboot

then, the u-boot environment has to be properly configured:

=> setenv mmc_loadk 'ext4load mmc ${mmcdev}:1 ${loadaddr} ${bootfile}'
=> setenv mmc_loadfdt 'ext4load mmc ${mmcdev}:1 ${fdtaddr} ${fdtfile}'
=> setenv mmc_loadsplash 'ext4load mmc ${mmcdev}:1 ${loadaddr} ${splashfile}; cp.b ${loadaddr} ${splashimage} ${filesize}'
=> saveenv

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