Standalone boot (BELK/BXELK)

Info Box Applies to Bora Applies to BORA Xpress

History

Version	Date	BXELK version	Hardware Part Nr	Notes
1.0.0	December 2016				2.0.0	March 2019	TBD	DBXF4110D2R EVBBX0000C0R

Introduction

This document shows some examples related to configuring Bora/BoraX for standalone operativity.

We'll explain how to program and configure a to boot in standalone mode, without the need of a system microSD card or an NFS server. Only the flash memories available on the SoM itself will be used to store persistently all the software required.

Use case #1

This configuration makes use of one of the most common partitioning schemes, that is:

• The NOR flash acts as boot memory; as such, it contains
  • U-Boot SPL
  • U-Boot
  • U-Boot redundant environment
  • Linux kernel image
  • Linux Device Tree Blob (DTB)
• The NAND flash contains the UBIFS root filesystem (read/write).

In essence, the bootstrap sequence looks like this:

• U-Boot fetches and programs the PL bitstream
• Then it fetches the Linux kernel binary images (kernel and DTB) from the on-board NOR flash memory
• Once started, the Linux kernel mount the root filesystem from a NAND partition.

This configuration was tested with the following testbed:

• SOM: DBXF4110D2R
• carrier board: EVBBX0000C0R
• software: BXELK 1.0.0

Program root file system in NAND flash

This is a common step for both booting options.

• Boot the system via SD or NFS as described into the System boot and recovery via microSD card and Booting the system via NFS
• By default, the NAND is already partitioned to allow booting from NAND-only (see next section) and, thus, some partitions are reserved for FSBL, 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)

root@bora:~# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00080000 00020000 "nand-SPL"
mtd1: 00080000 00020000 "nand-uboot"
mtd2: 00040000 00020000 "nand-uboot-env1"
mtd3: 00040000 00020000 "nand-uboot-env2"
mtd4: 00440000 00020000 "nand-bitstream"
mtd5: 00040000 00020000 "nand-device-tree"
mtd6: 00400000 00020000 "nand-linux"
mtd7: 1f600000 00020000 "nand-rootfs"

Please note that MTD partition index may change depending on 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@bora:~# ubiformat /dev/mtd7
ubiformat: mtd7 (nand), size 526385152 bytes (502.0 MiB), 4016 eraseblocks of 131072 bytes (128.0 KiB), min. I/O size 2048 bytes
libscan: scanning eraseblock 4015 -- 100 % complete
ubiformat: 4016 eraseblocks have valid erase counter, mean value is 2
ubiformat: formatting eraseblock 4015 -- 100 % complete
root@bora:~# ubiattach -m 7
[   95.732434] UBI: attaching mtd7 to ubi0
[  100.930047] UBI: scanning is finished
[  100.954932] UBI: attached mtd7 (name "nand-rootfs", size 502 MiB) to ubi0
[  100.961772] UBI: PEB size: 131072 bytes (128 KiB), LEB size: 126976 bytes
[  100.968534] UBI: min./max. I/O unit sizes: 2048/2048, sub-page size 2048
[  100.975248] UBI: VID header offset: 2048 (aligned 2048), data offset: 4096
[  100.982129] UBI: good PEBs: 4016, bad PEBs: 0, corrupted PEBs: 0
[  100.988100] UBI: user volume: 0, internal volumes: 1, max. volumes count: 128
[  100.995271] UBI: max/mean erase counter: 4/3, WL threshold: 4096, image sequence number: 1955579947
[  101.004308] UBI: available PEBs: 3852, total reserved PEBs: 164, PEBs reserved for bad PEB handling: 160
[  101.013959] UBI: background thread "ubi_bgt0d" started, PID 913
UBI device number 0, total 4016 LEBs (509935616 bytes, 486.3 MiB), available 3852 LEBs (489111552 bytes, 466.5 MiB), LEB size 126976 bytes (124.0 KiB)
root@bora:~# ubimkvol /dev/ubi0 -N rootfs -m
Set volume size to 489111552
Volume ID 0, size 3852 LEBs (489111552 bytes, 466.5 MiB), LEB size 126976 bytes (124.0 KiB), dynamic, name "rootfs", alignment 1

• 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
[  151.397013] UBIFS: default file-system created
[  151.402858] UBIFS: background thread "ubifs_bgt0_0" started, PID 918
[  151.529438] UBIFS: mounted UBI device 0, volume 0, name "rootfs"
[  151.535395] UBIFS: LEB size: 126976 bytes (124 KiB), min./max. I/O unit sizes: 2048 bytes/2048 bytes
[  151.544507] UBIFS: FS size: 487079936 bytes (464 MiB, 3836 LEBs), journal size 24379392 bytes (23 MiB, 192 LEBs)
[  151.554646] UBIFS: reserved for root: 4952683 bytes (4836 KiB)
[  151.560452] UBIFS: media format: w4/r0 (latest is w4/r0), UUID 447F1480-E173-4BE9-B5BE-A3EC1267F99E, small LPT model

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

tar zxvf belk-3.0.1_bora-image-devel-bora.tar.gz -C /mnt/nand

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

umount /mnt/nand/
ubidetach -m 7

E.g.

root@bora:~# umount /mnt/nand/
[  385.604146] UBIFS: un-mount UBI device 0, volume 0
[  385.608892] UBIFS: background thread "ubifs_bgt0_0" stops
root@bora:~# ubidetach -m 7
[  387.671411] UBI: detaching mtd7 from ubi0
[  387.677554] UBI: mtd7 is detached from ubi0
root@bora:~#

You can now safely reboot or turn off the system.

Program boot images

NOR flash

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

fdt_base=0x00780000
fpga_base=0x00180000
kernel_base=0x00800000
loadk=tftpboot ${loadaddr} ${bootfile}
loadfdt=tftpboot ${fdtaddr} ${fdtfile}
loadfpga=tftpboot ${loadaddr} ${fpgafile}
updatek=sf probe 0 0 0;sf erase ${kernel_base} +${filesize};sf write ${loadaddr} ${kernel_base} ${filesize}
updatefdt=sf probe 0 0 0;sf erase ${fdt_base} +${filesize};sf write ${fdtaddr} ${fdt_base} ${filesize}
updatefpga=sf probe 0 0 0;sf erase ${fpga_base} +${filesize};sf write ${loadaddr} ${fpga_base} ${filesize}
spi_loadk=sf read ${loadaddr} ${kernel_base} 0x800000
spi_loadfdt=sf read ${fdtaddr} ${fdt_base} 0x80000
spi_loadfpga=sf read ${loadaddr} ${fpga_base} 0x600000
program_fpga=run spi_loadfpga;fpga load 0 ${loadaddr} 0x5b3f0c

• Update the bootfile, fdtfile and fpgafile 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

zynq-uboot> sf probe; run loadfpga updatefpga loadk updatek loadfdt updatefdt

E.g.:

zynq-uboot> sf probe; run loadfpga updatefpga loadk updatek loadfdt updatefdt
SF: Detected S25FL128S_64K with page size 256 Bytes, erase size 64 KiB, total 16 MiB
Using Gem.e000b000 device
TFTP from server 192.168.0.23; our IP address is 192.168.0.209
Filename 'bora/borax-BELK-3.0.0-fpga.bin'.
Load address: 0x2080000
Loading: T #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         ###############################################################
         823.2 KiB/s
done
Bytes transferred = 5979916 (5b3f0c hex)
SF: Detected S25FL128S_64K with page size 256 Bytes, erase size 64 KiB, total 16 MiB
SF: 6029312 bytes @ 0x180000 Erased: OK
SF: 5979916 bytes @ 0x180000 Written: OK
Using Gem.e000b000 device
TFTP from server 192.168.0.23; our IP address is 192.168.0.209
Filename 'bora/linux/belk-3.0.0_uImage'.
Load address: 0x2080000
Loading: T #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         ##############################
         545.9 KiB/s
done
Bytes transferred = 3477184 (350ec0 hex)
SF: Detected S25FL128S_64K with page size 256 Bytes, erase size 64 KiB, total 16 MiB
SF: 3538944 bytes @ 0x800000 Erased: OK
SF: 3477184 bytes @ 0x800000 Written: OK
Using Gem.e000b000 device
TFTP from server 192.168.0.23; our IP address is 192.168.0.209
Filename 'bora/linux/belk-3.0.0_bora.dtb'.
Load address: 0x2000000
Loading: T ##
         2 KiB/s
done
Bytes transferred = 10019 (2723 hex)
SF: Detected S25FL128S_64K with page size 256 Bytes, erase size 64 KiB, total 16 MiB
SF: 65536 bytes @ 0x780000 Erased: OK
SF: 10019 bytes @ 0x780000 Written: OK

In U-Boot environment please set the following variables in order to be able to boot from NOR + NAND

nandargs=setenv bootargs ubi.mtd=7 root=ubi0_0 rootfstype=ubifs rw
spi_nand=sf probe; run program_fpga spi_loadk spi_loadfdt nandargs addcons addmisc; bootm ${loadaddr} - ${fdtaddr}

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

=> setenv bootcmd run spi_nand
=> saveenv

Use case #2

llandre@linuxserver2:/tftpboot/borax/elt$ python /devel/dave/bora-DBRx/fpga/fpga-bit-to-bin.py -f bitstream.bit bitstream.bin
Design name: TOP_LEVEL;UserID=0XFFFFFFFF;Version=2017.4
Partname 7z030sbg485
Date 2019/02/01
Time 16:38:59
found binary data: 5979916

Bora> nand info

Device 0: nand0, sector size 128 KiB
  Page size       2048 b
  OOB size          64 b
  Erase size    131072 b
  subpagesize      512 b
  options     0x       0
  bbt options 0x   20000
Bora> nand erase 0 3000000

NAND erase: device 0 offset 0x0, size 0x3000000
Erasing at 0x2fe0000 -- 100% complete.
OK
Bora> nand write ${loadaddr} 0 <INTERRUPT>
Bora> print ${filesize}
## Error: "8fc790" not defined
Bora> print
DBXx_test_result=test_passed
addcons=setenv bootargs ${bootargs} console=${console},115200n8 debug earlyprintk
addip=setenv bootargs ${bootargs} ip=${ipaddr}:${serverip}:${gateway}:${netmask}:${hostname}:${ethdev}
addmisc=setenv bootargs ${bootargs} cma=16M ${mtdparts}
baudrate=115200
bootaddr=0x101100
bootcmd=run net_nfs
bootdelay=3
bootfile=bora/linux/belk-4.0.0_uImage
bootscript=echo Running bootscript from ${recoverydev} ...; source ${loadaddr}
cb_configid#=ffffffff
cb_uniqueid#=00000000:00000000
configid_fixupfdt=if configid checkfdt ${fdtaddr} som_configid ${som_configid#}; then configid fdt_uniqueid ${fdtaddr}; fi
console=ttyPS0
ethact=ethernet@e000b000
ethaddr=00:50:C2:1E:AF:B3
ethdev=eth0
fdt_base=0x00780000
fdt_high=0x1F000000
fdtaddr=2000000
fdtcontroladdr=3ffa0a90
fdtfile=bora/linux/belk-4.0.0_bora.dtb
fileaddr=2080000
filesize=8fc790
fpga_base=0x00180000
fpgafile=bora/bora.bin
fsbl_base=0x40000
gateway=192.168.0.254
header_base=0
hostname=bora
ipaddr=192.168.0.81
jtag_vx=run vxargs; bootvx 0x200000
kernel_base=0x00800000
load=tftpboot ${loadaddr} bora/u-boot.bin
loadaddr=0x02080000
loadbootscript=fatload ${recoverydev} 0:1 ${loadaddr} ${script};
loadfdt=tftpboot ${fdtaddr} ${fdtfile}
loadfpga=tftpboot ${loadaddr} ${fpgafile}
loadfsbl=tftpboot ${loadaddr} bora/bora_fsbl.bin
loadhdr=tftpboot ${loadaddr} bora/boot_header
loadk=tftpboot ${loadaddr} ${bootfile}
loadvx=tftpboot ${loadaddr} ${vxfile}
mmcargs=setenv bootargs root=/dev/mmcblk0p${mmcpart} rootwait rw
mmcdev=0
mmcpart=2
mmcrecovery=mmc dev 0; mmc rescan; setenv recoverydev mmc; run recovery
modeboot=qspiboot
mtdids=nand0=pl353-nand
mtdparts=mtdparts=pl35x-nand:48M(data0),15M(data1),1M(data2),-(data3)
mtdparts1=mtdparts=pl353-nand:512K(spl),512K(uboot),256K(env1),256K(env2),4M(fpga),256K(fdt),4M(kernel),-(nand-ubi)
nand_erasesize=20000
nand_loadk=nand read ${loadaddr} kernel
nand_oobsize=40
nand_updatek=nand erase.part kernel; nand write ${loadaddr} nand-kernel ${filesize}
nand_writesize=800
nandargs=setenv bootargs ubi.mtd=7 root=ubi0_0 rootfstype=ubifs rw
net_nfs=ping ${serverip};run loadk loadfdt nfsargs addip addcons addmisc; run configid_fixupfdt; bootm ${loadaddr} - ${fdtaddr}
net_vx=run loadvx vxargs; bootvx ${loadaddr}
netmask=255.255.255.0
nfsargs=setenv bootargs root=/dev/nfs rw nfsroot=${serverip}:${rootpath},tcp
normalboot=net_nfs
program_fpga=run loadfpga;fpga load 0 ${loadaddr} 0x${filesize}
qspiboot=echo Booting from QSPI: use net_nfs && run net_nfs
ramdisk_size=0x200000
recovery=if run loadbootscript; then run bootscript; fi
rootpath=/opt/nfsroot/bora/belk-4.0.0
script=boot.scr
serial#_DBXx=00C5
serverip=192.168.0.13
som_configid#=00000005
som_uniqueid#=3a11013a:40b52447
stderr=serial@e0001000
stdin=serial@e0001000
stdout=serial@e0001000
u-boot_base=0x80000
update=sf probe 0 0 0;sf erase ${u-boot_base} +${filesize};sf write ${loadaddr} ${u-boot_base} ${filesize}
updatefdt=sf probe 0 0 0;sf erase ${fdt_base} +${filesize};sf write ${fdtaddr} ${fdt_base} ${filesize}
updatefpga=sf probe 0 0 0;sf erase ${fpga_base} +${filesize};sf write ${loadaddr} ${fpga_base} ${filesize}
updatefsbl=sf probe 0 0 0;sf erase ${fsbl_base} +${filesize};sf write ${loadaddr} ${fsbl_base} ${filesize}
updatehdr=sf probe 0 0 0;sf erase ${header_base} +${filesize};sf write ${loadaddr} ${header_base} ${filesize}
updatek=sf probe 0 0 0;sf erase ${kernel_base} +${filesize};sf write ${loadaddr} ${kernel_base} ${filesize}
usbrecovery=usb start; usb dev 0; setenv recoverydev usb; run recovery
vxargs=setenv bootargs gem(0,0)host:vxWorks.st h=${serverip} e=${ipaddr} g=${gatewayip} tn=${hostname} u=target pw=vxTarget f=0x0
vxfile=bora/vxWorks

Environment size: 3823/262139 bytes
Bora> nand write ${loadaddr} 0 ${filesize}

NAND write: device 0 offset 0x0, size 0x8fc790
 9422736 bytes written: OK
Bora> tftpboot ${loadaddr} borax/elt/bitstream.bit
Using ethernet@e000b000 device
TFTP from server 192.168.0.13; our IP address is 192.168.0.81
Filename 'borax/elt/bitstream.bit'.
Load address: 0x2080000
Loading: #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         ###############################################################
         2.6 MiB/s
done
Bytes transferred = 5980021 (5b3f75 hex)
Bora> nand erase 3000000 f00000

NAND erase: device 0 offset 0x3000000, size 0xf00000
Erasing at 0x3ee0000 -- 100% complete.
OK
Bora> nand write ${loadaddr} 3000000 ${filesize}

NAND write: device 0 offset 0x3000000, size 0x5b3f75
 5980021 bytes written: OK
Bora> nand erase 3f00000 100000

NAND erase: device 0 offset 0x3f00000, size 0x100000
Erasing at 0x3fe0000 -- 100% complete.
OK
Bora> tftpboot ${loadaddr} borax/elt/bora.dtb
Using ethernet@e000b000 device
TFTP from server 192.168.0.13; our IP address is 192.168.0.81
Filename 'borax/elt/bora.dtb'.
Load address: 0x2080000
Loading: ###
         746.1 KiB/s
done
Bytes transferred = 15280 (3bb0 hex)
Bora> nand write ${loadaddr} 3f00000 ${filesize}

NAND write: device 0 offset 0x3f00000, size 0x3bb0
 15280 bytes written: OK
Bora>

root@bora:~# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 03000000 00020000 "data0"
mtd1: 00f00000 00020000 "data1"
mtd2: 00100000 00020000 "data2"
mtd3: 3c000000 00020000 "data3"
root@bora:~# ubiformat /dev/mtd3
ubiformat: mtd3 (nand), size 1006632960 bytes (960.0 MiB), 7680 eraseblocks of 131072 bytes (128.0 KiB), min. I/O size 2048 bytes
libscan: scanning eraseblock 7679 -- 100 % complete
ubiformat: 7676 eraseblocks are supposedly empty
ubiformat: 4 bad eraseblocks found, numbers: 7676, 7677, 7678, 7679
ubiformat: formatting eraseblock 7679 -- 100 % complete
root@bora:~# ubiattach -m 3
[ 1149.075187] ubi0: attaching mtd3
[ 1154.062660] ubi0: scanning is finished
[ 1154.093813] ubi0: attached mtd3 (name "data3", size 960 MiB)
[ 1154.099516] ubi0: PEB size: 131072 bytes (128 KiB), LEB size: 129024 bytes
[ 1154.106479] ubi0: min./max. I/O unit sizes: 2048/2048, sub-page size 512
[ 1154.113172] ubi0: VID header offset: 512 (aligned 512), data offset: 2048
[ 1154.120026] ubi0: good PEBs: 7676, bad PEBs: 4, corrupted PEBs: 0
[ 1154.126302] ubi0: user volume: 0, internal volumes: 1, max. volumes count: 128
[ 1154.133591] ubi0: max/mean erase counter: 0/0, WL threshold: 4096, image sequence number: 248135964
[ 1154.142667] ubi0: available PEBs: 7516, total reserved PEBs: 160, PEBs reserved for bad PEB handling: 156
[ 1154.152304] ubi0: background thread "ubi_bgt0d" started, PID 870
UBI device number 0, total 7676 LEBs (990388224 bytes, 944.5 MiB), available 7516 LEBs (969744384 bytes, 924.8 MiB), LEB size 129024 bytes (126.0 KiB)
root@bora:~# ubimkvol /dev/ubi0 -N data3 -m
Set volume size to 969744384
Volume ID 0, size 7516 LEBs (969744384 bytes, 924.8 MiB), LEB size 129024 bytes (126.0 KiB), dynamic, name "data3", alignment 1
root@bora:~# ls -la /mnt/
total 16
drwxr-xr-x    4 root     root          4096 Mar 19  2018 .
drwxrwxr-x   16 541      502           4096 Jul  9 21:11 ..
drwxr-xr-x    2 root     root          4096 Mar 19  2018 tftpvideo
drwxr-xr-x    2 root     root          4096 Mar 19  2018 ubifs
root@bora:~# mkdir -p /mnt/data3
root@bora:~# mount -t ubifs ubi0_0 /mnt/data3
[ 1238.777228] UBIFS (ubi0:0): default file-system created
[ 1238.783887] UBIFS (ubi0:0): background thread "ubifs_bgt0_0" started, PID 878
[ 1238.913347] UBIFS (ubi0:0): UBIFS: mounted UBI device 0, volume 0, name "data3"
[ 1238.920577] UBIFS (ubi0:0): LEB size: 129024 bytes (126 KiB), min./max. I/O unit sizes: 2048 bytes/2048 bytes
[ 1238.930509] UBIFS (ubi0:0): FS size: 967421952 bytes (922 MiB, 7498 LEBs), journal size 33546240 bytes (31 MiB, 260 LEBs)
[ 1238.941440] UBIFS (ubi0:0): reserved for root: 4952683 bytes (4836 KiB)
[ 1238.948006] UBIFS (ubi0:0): media format: w4/r0 (latest is w4/r0), UUID B4CA7F10-B2AE-4C89-B2E1-59B38879E564, small LPT model
root@bora:~# mount
192.168.0.13:/opt/nfsroot/bora/belk-4.0.0 on / type nfs (rw,relatime,vers=2,rsize=4096,wsize=4096,namlen=255,hard,nolock,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=192.168.0.13,mountvers=1,mountproto=tcp,local_lock=all,addr=192.168.0.13)
devtmpfs on /dev type devtmpfs (rw,relatime,size=506608k,nr_inodes=126652,mode=755)
proc on /proc type proc (rw,relatime)
sysfs on /sys type sysfs (rw,relatime)
debugfs on /sys/kernel/debug type debugfs (rw,relatime)
tmpfs on /run type tmpfs (rw,nosuid,nodev,mode=755)
tmpfs on /var/volatile type tmpfs (rw,relatime)
devpts on /dev/pts type devpts (rw,relatime,gid=5,mode=620,ptmxmode=000)
ubi0_0 on /mnt/data3 type ubifs (rw,relatime)
root@bora:~# df
Filesystem           1K-blocks      Used Available Use% Mounted on
192.168.0.13:/opt/nfsroot/bora/belk-4.0.0
                     103080204  95026920   2810460  97% /
devtmpfs                506608         0    506608   0% /dev
tmpfs                   515312        48    515264   0% /run
tmpfs                   515312        48    515264   0% /var/volatile
ubi0_0                  887868        16    883016   0% /mnt/data3
root@bora:~#

Bora> setenv nandboot2 'run loadunand loadfdtnand nandargs2 addip addcons addmisc; run configid_fixupfdt; bootm ${loadaddr} - ${fdtaddr}'
Bora> savee
Saving Environment to SPI Flash...
SF: Detected s25fl128s_64k with page size 256 Bytes, erase size 64 KiB, total 32 MiB
Erasing SPI flash...Writing to SPI flash...done
Valid environment: 1
Bora> edit loadunand
edit: Bora> nand help
nand - NAND sub-system

Usage:
nand info - show available NAND devices
nand device [dev] - show or set current device
nand read - addr off|partition size
nand write - addr off|partition size
    read/write 'size' bytes starting at offset 'off'
    to/from memory address 'addr', skipping bad blocks.
nand read.raw - addr off|partition [count]
nand write.raw[.noverify] - addr off|partition [count]
    Use read.raw/write.raw to avoid ECC and access the flash as-is.
nand erase[.spread] [clean] off size - erase 'size' bytes from offset 'off'
    With '.spread', erase enough for given file size, otherwise,
    'size' includes skipped bad blocks.
nand erase.part [clean] partition - erase entire mtd partition'
nand erase.chip [clean] - erase entire chip'
nand bad - show bad blocks
nand dump[.oob] off - dump page
nand scrub [-y] off size | scrub.part partition | scrub.chip
    really clean NAND erasing bad blocks (UNSAFE)
nand markbad off [...] - mark bad block(s) at offset (UNSAFE)
nand biterr off - make a bit error at offset (UNSAFE)
nand lock [tight] [status]
    bring nand to lock state or display locked pages
nand unlock[.allexcept] [offset] [size] - unlock section
Bora> edit loadunand
edit: nand read ${loadaddr} 0 3000000
Bora> edit loadfdtnand
edit: nand read ${fdtaddr} 3000000 f00000
Bora> edit loadfdtnand
edit: nand read ${fdtaddr} 3f00000 100000
Bora> savee
Saving Environment to SPI Flash...
Erasing SPI flash...Writing to SPI flash...done
Valid environment: 2
Bora> edit nandargs2
edit: setenv bootargs ''