Thks for the tip.
I did try to install
openwrt-19.07.5-mvebu-cortexa9-linksys_wrt3200acm-squashfs-sysupgrade.bin
and
openwrt-19.07.4-mvebu-cortexa9-linksys_wrt3200acm-squashfs-sysupgrade.bin
Here the console output:
There is an "sysupgrade successful" message.
Sending KILL to remaining processes ...
Switching to ramdisk...
[ 2971.361838] UBIFS (ubi0:1): background thread "ubifs_bgt0_1" stops
[ 2971.422414] UBIFS (ubi0:1): un-mount UBI device 0
Performing system upgrade...
Read error on /dev/mtd1: No error information
Error: can't write fw_env to flash
Unlocking kernel1 ...
Writing from <stdin> to kernel1 ...
[ 2972.189085] ubi2: attaching mtd6
[ 2972.383360] ubi2: scanning is finished
[ 2972.391328] ubi2: attached mtd6 (name "rootfs1", size 74 MiB)
[ 2972.397112] ubi2: PEB size: 131072 bytes (128 KiB), LEB size: 126976 bytes
[ 2972.404016] ubi2: min./max. I/O unit sizes: 2048/2048, sub-page size 2048
[ 2972.410837] ubi2: VID header offset: 2048 (aligned 2048), data offset: 4096
[ 2972.417831] ubi2: good PEBs: 592, bad PEBs: 0, corrupted PEBs: 0
[ 2972.423863] ubi2: user volume: 2, internal volumes: 1, max. volumes count: 12 8
[ 2972.431120] ubi2: max/mean erase counter: 4/2, WL threshold: 4096, image sequ ence number: 140946296
[ 2972.440209] ubi2: available PEBs: 0, total reserved PEBs: 592, PEBs reserved for bad PEB handling: 40
[ 2972.449476] ubi2: background thread "ubi_bgt2d" started, PID 22777
UBI device number 2, total 592 LEBs (75169792 bytes, 71.6 MiB), available 0 LEBs (0 bytes), LEB size 126976 bytes (124.0 KiB)
Volume ID 0, size 26 LEBs (3301376 bytes, 3.1 MiB), LEB size 126976 bytes (124.0 KiB), dynamic, name "rootfs", alignment 1
Set volume size to 66281472
Volume ID 1, size 522 LEBs (66281472 bytes, 63.2 MiB), LEB size 126976 bytes (12 4.0 KiB), dynamic, name "rootfs_data", alignment 1
[ 2973.319577] UBIFS (ubi2:1): default file-system created
[ 2973.325214] UBIFS (ubi2:1): background thread "ubifs_bgt2_1" started, PID 228 55
[ 2973.357290] UBIFS (ubi2:1): UBIFS: mounted UBI device 2, volume 1, name "root fs_data"
[ 2973.365167] UBIFS (ubi2:1): LEB size: 126976 bytes (124 KiB), min./max. I/O u nit sizes: 2048 bytes/2048 bytes
[ 2973.375132] UBIFS (ubi2:1): FS size: 65011712 bytes (62 MiB, 512 LEBs), journ al size 3301376 bytes (3 MiB, 26 LEBs)
[ 2973.385617] UBIFS (ubi2:1): reserved for root: 3070663 bytes (2998 KiB)
[ 2973.392261] UBIFS (ubi2:1): media format: w4/r0 (latest is w5/r0), UUID CFBB7 A0A-89D3-4301-8B98-F4AD56D8AA56, small LPT model
[ 2973.464726] UBIFS (ubi2:1): un-mount UBI device 2
[ 2973.469471] UBIFS (ubi2:1): background thread "ubifs_bgt2_1" stops
sysupgrade successful
umount: can't unmount /dev: Resource busy
[ 2973.644869] UBIFS (ubi1:0): un-mount UBI device 1
[ 2973.649601] UBIFS (ubi1:0): background thread "ubifs_bgt1_0" stops
umount: can't unmount /tmp: Resource busy
BootROM - 1.73
Booting from NAND flash
General initialization - Version: 1.0.0
AVS selection from EFUSE disabled (Skip reading EFUSE values)
mvSysEnvIsFlavourReduced: TWSI Read of 'flavor' failed
Detected Device ID 6820
High speed PHY - Version: 2.0
Init RD NAS topology Serdes Lane 3 is USB3
Serdes Lane 4 is SGMII
board SerDes lanes topology details:
| Lane # | Speed| Type |
------------------------------|
| 0 | 6 | SATA0 |
| 1 | 5 | PCIe0 |
| 2 | 6 | SATA1 |
| 3 | 5 | USB3 HOST1 |
| 4 | 5 | PCIe1 |
| 5 | 0 | SGMII2 |
-------------------------------
:** Link is Gen1, check the EP capability
PCIe, Idx 0: Link upgraded to Gen2 based on client cpabilities
:** Link is Gen1, check the EP capability
PCIe, Idx 1: remains Gen1
High speed PHY - Ended Successfully
DDR3 Training Sequence - Ver TIP-1.46.0
mvSysEnvGetTopologyUpdateInfo: TWSI Read failed
DDR3 Training Sequence - Switching XBAR Window to FastPath Window
DDR3 Training Sequence - Ended Successfully
Not detected suspend to RAM indication
BootROM: Image checksum verification PASSED
U-Boot 2013.01 (Sep 25 2017 - 11:42:52) Marvell version: 2015_T1.QA.0p16
Boot version : v1.0.0
Board: RD-NAS-88F6820-DDR3
SoC: MV88F6820 Rev A0
running 2 CPUs
CPU: ARM Cortex A9 MPCore (Rev 1) LE
CPU 0
CPU @ 1866 [MHz]
L2 @ 933 [MHz]
TClock @ 200 [MHz]
DDR3 @ 933 [MHz]
DDR3 32 Bit Width,FastPath Memory Access, DLB Enabled, ECC Disabled
DRAM: 512 MiB
NAND: 256 MiB
MMC: mv_sdh: 0
#### auto_recovery ####
[u_env] get auto_recovery == yes
[u_env] get auto_recovery == yes
[u_env] get boot_part == 2
[u_env] get boot_part_ready == 3
auto_recovery enabled:1, boot_part:2, boot_part_ready:3
[boot_count_read] block:0x220000, size:128KB, records:64
[boot_count_read_record] boot_count:0, next_record:10
[boot_count_write] erase:0, auto_recovery->block_offset:0x220000 offset=0x225000
Updating boot_count ...
[boot_count_write] offset:0x225000 , length:2048
done
PCI-e 0 (IF 0 - bus 0) Root Complex Interface, Detected Link X1, GEN 2.0
PCI-e 1 (IF 1 - bus 1) Root Complex Interface, Detected Link X1, GEN 1.1
USB2.0 0: Host Mode
USB3.0 1: Host Mode
USB3.0 0: Host Mode