XELK-AN-007: Migrating u-boot to SPL

Info Box Applies to Axel Ultra Applies to AXEL ESATTA Applies to Axel Lite Applies to AXEL Lite Application Notes

This application note has been validated starting from the XELK 3.0.x kit version.

History

Version	Date	XELK version	Notes
1.0.0	Aug 2019	3.5.0	First SPL release

Introduction

Starting from XELK 3.5.0 binary version, u-boot supports the SPL first-stage bootloader and second-stage bootloader (the proper u-boot complete binary).

It is then required to update the u-boot on AXEL LITE SoM using some new u-boot environment variables: those vars will be present and ready to be used on the new SPL default environment.

Here below, you can find a step-by-step user's guide for updating u-boot to the new SPL version.

u-boot commands

In order to program the uboot SPL binaries (SPL and u-boot.img) some new environment variables are useful for loading the binaries from a tftp server and store them on the storage boot device (i.e. NOR SPI and SD).

The load commands are:

=> pri load_spl
load_spl=tftp ${loadaddr} ${spl}
=> pri load_uboot
load_uboot=tftp ${loaddr} ${ubootimg}
=> 

and the related update commands are (for example for the SD card storage device):

=> pri mmc_update_spl
mmc_update_spl=mmc dev; setexpr blocks ${filesize} / 0x200; setexpr blocks ${blocks} + 1; mmc write ${loadaddr} 2 ${blocks}
=> pri mmc_update_uboot
mmc_update_uboot=mmc dev; setexpr blocks ${filesize} / 0x200; setexpr blocks ${blocks} + 1; mmc write ${loadaddr} 0x8a  ${blocks}
=>

update u-boot on NOR SPI

In the following example, it is assumed that the u-boot binary files are present on the tftp server /tftpboot/ directory:

• create the SPL commands for loading and programming

=> setenv load_spl 'tftp ${loadaddr} ${spl}'
=> setenv load_uboot 'tftp ${loaddr} ${ubootimg}'
=> setenv spi_update_spl 'sf probe; sf erase 0 10000;sf write ${loadaddr} 400 ${filesize}'
=> setenv spi_update_uboot 'sf probe; sf erase 10000 f0000;sf write ${loadaddr} 10000 ${filesize}'
=> saveenv
Saving Environment to SPI Flash...
SF: Detected S25FL256S_64K with page size 256 Bytes, erase size 64 KiB, total 32 MiB
Erasing SPI flash...Writing to SPI flash...done
Valid environment: 1
=> 

• configure the spl and ubootimg vars containing the SPL filenames to be loaded:

=> setenv spl 'axel/xelk-3.5.0_mx6qdlaxel_spi_SPL'
=> setenv ubootimg 'axel/xelk-3.5.0_mx6qdlaxel_spi_u-boot.img'
=> saveenv
Saving Environment to SPI Flash...
SF: Detected S25FL256S_64K with page size 256 Bytes, erase size 64 KiB, total 32 MiB
Erasing SPI flash...Writing to SPI flash...done
Valid environment: 2
=>

• load and program the SPL binaries (i.e. from the running tftp server on the XELK 3 VM):

=> run load_spl
FEC Waiting for PHY auto negotiation to complete. done
Using FEC device
TFTP from server 192.168.0.125; our IP address is 192.168.0.96
Filename 'axel/xelk-3.5.0_mx6qdlaxel_spi_SPL'.
Load address: 0x12000000
Loading: ############
         966.8 KiB/s
done
Bytes transferred = 60416 (ec00 hex)
=> run spi_update_spl
SF: Detected S25FL256S_64K with page size 256 Bytes, erase size 64 KiB, total 32 MiB
SF: 65536 bytes @ 0x0 Erased: OK
device 0 offset 0x400, size 0xec00
SF: 60416 bytes @ 0x400 Written: OK
=> run load_uboot
Using FEC device
TFTP from server 192.168.0.125; our IP address is 192.168.0.96
Filename 'axel/xelk-3.5.0_mx6qdlaxel_spi_u-boot.img'.
Load address: 0x12000000
Loading: #################################################################
         ##################################
         869.1 KiB/s
done
Bytes transferred = 502364 (7aa5c hex)
=> run spi_update_uboot
SF: Detected S25FL256S_64K with page size 256 Bytes, erase size 64 KiB, total 32 MiB
SF: 983040 bytes @ 0x10000 Erased: OK
device 0 offset 0x10000, size 0x7aa5c
SF: 502364 bytes @ 0x10000 Written: OK
=>

Now, u-boot SPL are ready to be started issuing a reset command:

=> reset
resetting ...

U-Boot SPL 2016.03-xelk-3.5.0 (Apr 19 2019 - 23:37:16)
SOM ConfigID#: 00000003
Trying to boot from SPI


U-Boot 2016.03-xelk-3.5.0 (Apr 19 2019 - 23:37:16 +0200), Build: jenkins-XELK-u-boot-62

CPU:   Freescale i.MX6Q rev1.5 996 MHz (running at 792 MHz)
CPU:   Automotive temperature grade (-40C to 125C) at 56C
Reset cause: POR
Environment: SPI Flash
I2C:   ready
DRAM:  2 GiB
Relocating to 8ff30000, new gd at 8df2feb8, sp at 8df2fe90
PMIC:  PFUZE100 ID=0x10
NAND:  512 MiB
MMC:   FSL_SDHC: 0
SF: Detected S25FL256S_64K with page size 256 Bytes, erase size 64 KiB, total 32 MiB
WARNING: CB ConfigID on block 0 is UNLOCKED
Display: LDB-AM-800480STMQW-TA1-SBCX-REVB (800x480)
SF: Detected S25FL256S_64K with page size 256 Bytes, erase size 64 KiB, total 32 MiB
device 0 offset 0xa00000, size 0x400000
SF: 4194304 bytes @ 0xa00000 Read: OK
Error: no valid bmp image at 20000002
In:    serial
Out:   serial
Err:   serial
SOM ConfigID#: 00000003
SOM UniqueID#: df646299:0b0579d4
CB ConfigID#: 00000012
CB UniqueID#: 3e00000c:de36b32d
Board: MX6Q-AxelLite on SBCX
Fastboot: unsupported boot devices
SATA isn't buildin
Net:   FEC [PRIME]
Warning: FEC (eth0) using random MAC address - 36:5c:b9:6e:08:8e

Normal Boot
Hit ENTER within 1 seconds to stop autoboot
=>

update u-boot on SD card

• configure the spl and ubootimg vars containing the SPL filenames to be loaded:

=> setenv spl 'axel/xelk-3.5.0_mx6qdlaxel_SPL'
=> setenv ubootimg 'axel/xelk-3.5.0_mx6qdlaxel_u-boot.img'
=>

• create the SPL commands for loading and programming

=> setenv load_spl 'tftp ${loadaddr} ${spl}'
=> setenv load_uboot 'tftp ${loaddr} ${ubootimg}'
=> setenv mmc_update_spl 'mmc dev; setexpr blocks ${filesize} / 0x200; setexpr blocks ${blocks} + 1; mmc write ${loadaddr} 2 ${blocks}'
=> setenv mmc_update_uboot 'mmc dev; setexpr blocks ${filesize} / 0x200; setexpr blocks ${blocks} + 1; mmc write ${loadaddr} 0x8a  ${blocks}'

• load and program the SPL binaries (i.e. from the running tftp server on the XELK 3 VM):

=> run load_spl
Using FEC device
TFTP from server 192.168.0.125; our IP address is 192.168.0.96
Filename 'axel/xelk-3.5.0_mx6qdlaxel_SPL'.
Load address: 0x12000000
Loading: ############
         1 MiB/s
done
Bytes transferred = 60416 (ec00 hex)
=> run mmc_update_spl
switch to partitions #0, OK
mmc0 is current device (SD)

MMC write: dev # 0, block # 2, count 119 ... 119 blocks written: OK
=> run load_uboot
Using FEC device
TFTP from server 192.168.0.125; our IP address is 192.168.0.96
Filename 'axel/xelk-3.5.0_mx6qdlaxel_u-boot.img'.
Load address: 0x12000000
Loading: #################################################################
         ##################################
         1.3 MiB/s
done
Bytes transferred = 502268 (7a9fc hex)
=> run mmc_update_uboot
switch to partitions #0, OK
mmc0 is current device (SD)

MMC write: dev # 0, block # 138, count 981 ... 981 blocks written: OK
=>

Insert the DIP header on the pin selecting the BOOT_MODE_SEL from SD card and reset the board:

=> reset
resetting ...

U-Boot SPL 2016.03-xelk-3.5.0 (Apr 19 2019 - 23:36:21)
SOM ConfigID#: 00000003
Trying to boot from MMC


U-Boot 2016.03-xelk-3.5.0 (Apr 19 2019 - 23:36:21 +0200), Build: jenkins-XELK-u-boot-62

CPU:   Freescale i.MX6Q rev1.5 996 MHz (running at 792 MHz)
CPU:   Automotive temperature grade (-40C to 125C) at 57C
Reset cause: POR
Environment: MMC
I2C:   ready
DRAM:  2 GiB
Relocating to 8ff30000, new gd at 8df2feb8, sp at 8df2fe90
PMIC:  PFUZE100 ID=0x10
NAND:  512 MiB
MMC:   FSL_SDHC: 0
WARNING: CB ConfigID on block 0 is UNLOCKED
Display: LDB-AM-800480STMQW-TA1-SBCX-REVB (800x480)
reading splash_image.bmp
1036854 bytes read in 73 ms (13.5 MiB/s)
In:    serial
Out:   serial
Err:   serial
SOM ConfigID#: 00000003
SOM UniqueID#: df646299:0b0579d4
CB ConfigID#: 00000012
CB UniqueID#: 3e00000c:de36b32d
Board: MX6Q-AxelLite on SBCX
switch to partitions #0, OK
mmc0 is current device (SD)
flash target is MMC:0
Bad partition index:2 for partition:recovery
Bad partition index:5 for partition:system
Bad partition index:4 for partition:data
Net:   FEC [PRIME]
Normal Boot
Hit ENTER within 1 seconds to stop autoboot
=>

As you can see, respect to the NOR SPI, the u-boot binaries for the SD card uses the environment on SD (labelled MMC on u-boot code):

Environment: MMC

update u-boot on NAND flash

The SPL and u-boot image, must be flashed on NAND using the NXP kobs-ng utility. This tool is required for writing correct information needed by bootrom to identify the NAND as a boot device.

N.B. for programming the second stage, the nandwrite command has to identify a proper mtd part witch correct size. For this reason, the mtdparts variable has to be modified for writing the complete u-boot image.

The following steps are therefore necessary:

1. boot the system via SD on NFS
2. uses a rfs with kobs-ng utility available on it (e.g. DAVE's rfs provided with XELK)
3. copy the related u-boot ans SPL files on nfs /home/root (for example)
4. execute kobs-ng passing the parameters for flashing the SPL on NAND
5. execute nandwrite to flash uboot image on NAND

• configure the mtdparts

=> setenv mtdparts 'mtdparts=gpmi-nand:2M(nand-SPL),6M(nand-uboot),1M(nand-env1),1M(nand-env2),1M(nand-fdt),1M(nand-spare),8M(nand-kernel),4M(nand-splash),-(nand-ubi)'

• configure u-boot vars for booting from NFS

=> setenv bootfile axel/xelk-3.0.8_uImage
=> setenv fdtfile axel/xelk-3.0.8_imx6dl-sbcx-cb0012.dtb
=> setenv rootpath /home/dvdk/axel/rfs/axel/
=> setenv serverip 192.168.0.125
=> run net_nfs

• boot from NFS

=> run net_nfs
Using FEC device
TFTP from server 192.168.0.125; our IP address is 192.168.0.90
Filename 'axel/xelk-3.0.8_uImage'.
Load address: 0x12000000
Loading: #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         ##################################################
         1.3 MiB/s
done
Bytes transferred = 6576424 (645928 hex)
Using FEC device
TFTP from server 192.168.0.125; our IP address is 192.168.0.90
Filename 'axel/xelk-3.0.8_imx6dl-sbcx-cb0012.dtb'.
Load address: 0x18000000
Loading: #########
         764.6 KiB/s
done
Bytes transferred = 45457 (b191 hex)
FDT: override 'som_uniqueid' with 'ea9ae213:041b71d4'
FDT: override 'cb_uniqueid' with '3e00000c:de36b32d'
## Booting kernel from Legacy Image at 12000000 ...
   Image Name:   Linux-4.1.15-xelk-3.0.8
   Image Type:   ARM Linux Kernel Image (uncompressed)
   Data Size:    6576360 Bytes = 6.3 MiB
   Load Address: 10008000
   Entry Point:  10008000
   Verifying Checksum ... OK
## Flattened Device Tree blob at 18000000
   Booting using the fdt blob at 0x18000000
   Loading Kernel Image ... OK
   reserving fdt memory region: addr=18000000 size=c000
   Using Device Tree in place at 18000000, end 1800efff
switch to ldo_bypass mode!
Frame buffer: configure splashscreen reserved memory to 0x4e000000 (2 MiB)
WARNING: could not find 2nd splashscreen reserved memory path

Starting kernel ...

[    0.000000] Booting Linux on physical CPU 0x0
[    0.000000] Linux version 4.1.15-xelk-3.0.8 (jenkins@linuxserver2) (gcc version 5.2.0 (GCC) ) #1 SMP PREEMPT Mon Mar 18 23:38:48 CET 2019
[    0.000000] CPU: ARMv7 Processor [412fc09a] revision 10 (ARMv7), cr=10c53c7d
[    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[    0.000000] Machine model: AxelLite DL on SBCX CB0012
[    0.000000] Reserved memory: created ipuv3_fb memory pool at 0x4e000000, size 2 MiB
[    0.000000] Reserved memory: initialized node splashscreen, compatible id fsl,ipuv3-fb
[    0.000000] Memory policy: Data cache writealloc
[    0.000000] PERCPU: Embedded 12 pages/cpu @bf7bc000 s16960 r8192 d24000 u49152
[    0.000000] Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 259584
[    0.000000] Kernel command line: root=/dev/nfs rw nfsroot=192.168.0.125:/home/dvdk/axel/rfs/axel/,v3,tcp ip=192.168.0.90:192.168.0.125::255.255.255.0:xelk:eth0:off panic=1 console=ttymxc2,115200 vmalloc=400M mtdparts=gpmi-nand:8M(nand-uboot),1M(nand-env1),1M(nand-env2),1M(nand-fdt),1M(nand-spare),8M(nand-kernel),4M(nand-splash),-(nand-ubi);spi0.0:1M(spi-uboot),256k(spi-env1),256k(spi-env2),512k(spi-dtb),8M(spi-kernel),4M(spi-splash),-(spi-free)
...
...
...
Starting Linux NFC daemon
Starting crond: OK
Running local boot scripts (/etc/rc.local).

Freescale i.MX Release Distro 4.1.15-2.0.1 imx6qxelk /dev/ttymxc2

imx6qxelk login: root
root@imx6qxelk:~#

• on the VM, copy the NAND u-boot binaries on the /home/root NFS directory:

dvdk@vagrant-ubuntu-trusty-64:~$ sudo cp /tftpboot/axel/xelk-3.5.0_mx6qdlaxel_nand_* /home/dvdk/axel/rfs/axel/home/root/
[sudo] password for dvdk: 
dvdk@vagrant-ubuntu-trusty-64:~$ sudo ls -la /home/dvdk/axel/rfs/axel/home/root/
total 568
drwx------ 2 root root   4096 Aug 13 10:34 .
drwxr-xr-x 3 root root   4096 Nov  9  2017 ..
-rw-r--r-- 1 root root     51 Nov  9  2017 .profile
-rw------- 1 root root      2 Nov 21  2017 .python-history
-rw-r--r-- 1 root root  60416 Aug 13 10:34 xelk-3.5.0_mx6qdlaxel_nand_SPL
-rw-r--r-- 1 root root 502780 Aug 13 10:34 xelk-3.5.0_mx6qdlaxel_nand_u-boot.img
dvdk@vagrant-ubuntu-trusty-64:~$ 

• execute kobs-ng for u-boot SPL programming

root@imx6qxelk:~# kobs-ng -x -v -w xelk-3.5.0_mx6qdlaxel_nand_SPL
MTD CONFIG:
  chip_0_device_path = "/dev/mtd0"
  chip_1_device_path = "(null)"
  search_exponent = 2
  data_setup_time = 80
  data_hold_time = 60
  address_setup_time = 25
  data_sample_time = 6
  row_address_size = 3
  column_address_size = 2
  read_command_code1 = 0
  read_command_code2 = 48
  boot_stream_major_version = 1
  boot_stream_minor_version = 0
  boot_stream_sub_version = 0
  ncb_version = 3
  boot_stream_1_address = 0
  boot_stream_2_address = 0
         -- We add the 1k-padding to the uboot.
.tmp_kobs_ng: verifying using key '00000000000000000000000000000000'
.tmp_kobs_ng: is a valid bootstream for key '00000000000000000000000000000000'
mtd: use new bch layout raw access mode
mtd: opening: "/dev/mtd0"
NFC geometry :
        ECC Strength       : 2
        Page Size in Bytes : 2071
        Metadata size      : 10
        ECC Chunk Size in byte : 512
        ECC Chunk count        : 4
        Block Mark Byte Offset : 2028
        Block Mark Bit Offset  : 2
====================================================
mtd: opened '/dev/mtd0' - '(null)'
mtd: max_boot_stream_size_in_bytes = 3670016
mtd: boot_stream_size_in_bytes = 61440
mtd: boot_stream_size_in_pages = 30
mtd: #1 0x00100000 - 0x00480000 (0x0010f000)
mtd: #2 0x00480000 - 0x00800000 (0x0048f000)
FCB
  m_u32Checksum = 0x00000000
  m_u32FingerPrint = 0x20424346
  m_u32Version = 0x01000000
  m_NANDTiming.m_u8DataSetup = 80
  m_NANDTiming.m_u8DataHold = 60
  m_NANDTiming.m_u8AddressSetup = 25
  m_NANDTiming.m_u8DSAMPLE_TIME = 6
  m_u32PageDataSize = 2048
  m_u32TotalPageSize = 2112
  m_u32SectorsPerBlock = 64
  m_u32NumberOfNANDs = 0
  m_u32TotalInternalDie = 0
  m_u32CellType = 0
  m_u32EccBlockNEccType = 1
  m_u32EccBlock0Size = 512
  m_u32EccBlockNSize = 512
  m_u32EccBlock0EccType = 1
  m_u32MetadataBytes = 10
  m_u32NumEccBlocksPerPage = 3
  m_u32EccBlockNEccLevelSDK = 0
  m_u32EccBlock0SizeSDK = 0
  m_u32EccBlockNSizeSDK = 0
  m_u32EccBlock0EccLevelSDK = 0
  m_u32NumEccBlocksPerPageSDK = 0
  m_u32MetadataBytesSDK = 0
  m_u32EraseThreshold = 0
  m_u32Firmware1_startingPage = 512
  m_u32Firmware2_startingPage = 2304
  m_u32PagesInFirmware1 = 30
  m_u32PagesInFirmware2 = 30
  m_u32DBBTSearchAreaStartAddress = 256
  m_u32BadBlockMarkerByte = 2028
  m_u32BadBlockMarkerStartBit = 2
  m_u32BBMarkerPhysicalOffset = 2048
  m_u32BCHType = 0
  m_NANDTMTiming.m_u32TMTiming2_ReadLatency = 0
  m_NANDTMTiming.m_u32TMTiming2_PreambleDelay = 0
  m_NANDTMTiming.m_u32TMTiming2_CEDelay = 0
  m_NANDTMTiming.m_u32TMTiming2_PostambleDelay = 0
  m_NANDTMTiming.m_u32TMTiming2_CmdAddPause = 0
  m_NANDTMTiming.m_u32TMTiming2_DataPause = 0
  m_NANDTMTiming.m_u32TMSpeed = 0
  m_NANDTMTiming.m_u32TMTiming1_BusyTimeout = 0
  m_u32DISBBM = 0
  m_u32BBMarkerPhysicalOffsetInSpareData = 0
DBBT
  m_u32Checksum = 0x00000000
  m_u32FingerPrint = 0x54424244
  m_u32Version = 0x01000000
  m_u32DBBTNumOfPages = 0
Firmware: image #0 @ 0x100000 size 0xf000 - available 0x380000
Firmware: image #1 @ 0x480000 size 0xf000 - available 0x380000
-------------- Start to write the [ FCB ] -----
mtd: erasing @0:0x0-0x20000
mtd: Writing FCB0 [ @0:0x0 ] (840) *
mtd: erasing @0:0x20000-0x40000
mtd: Writing FCB1 [ @0:0x20000 ] (840) *
mtd: erasing @0:0x40000-0x60000
mtd: Writing FCB2 [ @0:0x40000 ] (840) *
mtd: erasing @0:0x60000-0x80000
mtd: Writing FCB3 [ @0:0x60000 ] (840) *
mtd_commit_bcb(FCB): status 0

-------------- Start to write the [ DBBT ] -----
mtd: erasing @0:0x80000-0xa0000
mtd: Writing DBBT0 [ @0:0x80000 ] (800) *
mtd: erasing @0:0xa0000-0xc0000
mtd: Writing DBBT1 [ @0:0xa0000 ] (800) *
mtd: erasing @0:0xc0000-0xe0000
mtd: Writing DBBT2 [ @0:0xc0000 ] (800) *
mtd: erasing @0:0xe0000-0x100000
mtd: Writing DBBT3 [ @0:0xe0000 ] (800) *
mtd_commit_bcb(DBBT): status 0

---------- Start to write the [ .tmp_kobs_ng ]----
mtd: Writting .tmp_kobs_ng: #0 @0: 0x00100000 - 0x0010f000
mtd: erasing @0:0x100000-0x120000
mtd: We write one page for save guard. *
mtd: Writting .tmp_kobs_ng: #1 @0: 0x00480000 - 0x0048f000
mtd: erasing @0:0x480000-0x4a0000
mtd: We write one page for save guard. *
root@imx6qxelk:~# 

• erase the mtd part with flash_erase

root@imx6qxelk:~# flash_erase /dev/mtd1 0 0

• execute nandwrite for second stage programming

root@imx6qxelk:~# nandwrite -p /dev/mtd1 xelk-3.5.0_mx6qdlaxel_nand_u-boot.img
Writing data to block 0 at offset 0x0
Writing data to block 1 at offset 0x20000
Writing data to block 2 at offset 0x40000
Writing data to block 3 at offset 0x60000
root@imx6qxelk:~#

• reboot and starts SPL fron NAND

root@imx6qxelk:~# reboot

Broadcast message from root@imx6qxelk (ttymxc2) (Thu Nov  9 06:08:11 2017):
The system is going down for reboot NOW!
...
...
...
Rebooting... [  515.784981] reboot: Restarting system

U-Boot SPL 2016.03-xelk-3.5.0 (Apr 19 2019 - 23:37:42)
SOM ConfigID#: 00000001
Trying to boot from NAND
NAND : 1024 MiB


U-Boot 2016.03-xelk-3.5.0 (Apr 19 2019 - 23:37:42 +0200), Build: jenkins-XELK-u-boot-62

CPU:   Freescale i.MX6DL rev1.3 at 792MHz
CPU:   Industrial temperature grade (-40C to 105C) at 56C
Reset cause: POR
Environment: NAND
I2C:   ready
DRAM:  1 GiB
Relocating to 4ff30000, new gd at 4df2feb8, sp at 4df2fe90
PMIC:  PFUZE100 ID=0x10
NAND:  1024 MiB
MMC:   FSL_SDHC: 0
WARNING: CB ConfigID on block 0 is UNLOCKED
Display: LDB-AM-800480STMQW-TA1-SBCX-REVB (800x480)

NAND read: device 0 offset 0x1400000, size 0x1c2036
 1843254 bytes read: OK
In:    serial
Out:   serial
Err:   serial
SOM ConfigID#: 00000001
SOM UniqueID#: ea9ae213:041b71d4
CB ConfigID#: 00000012
CB UniqueID#: 3e00000c:de36b32d
Board: MX6DL-AxelLite on SBCX
Fastboot: unsupported boot devices
Net:   FEC [PRIME]
Warning: FEC (eth0) using random MAC address - a6:1d:61:82:c9:0f

Normal Boot
Hit ENTER within 1 seconds to stop autoboot
=>

As you can see, the SPL code recognizes the NAND flash and properly loads the correct u-boot second-stage for its execution:

U-Boot SPL 2016.03-xelk-3.5.0 (Apr 19 2019 - 23:37:42)
SOM ConfigID#: 00000001
Trying to boot from NAND
NAND : 1024 MiB