Little thing I learned about #UBoot and its EXT4 support: it doesn't support 64-bit filesystems or metadata checksums.

The latter is a bit of a shame as it might detect some corruption issues, but the latter merely restricts the block device to 2TB. Who needs a `/boot` that big? (Or has the money for a ≥2TB MicroSD card?)

```
mkfs.ext4 -O ^64bit,^metadata_csum ${partition}
```

If you fail to do this, older U-Boot (2014-era) will just ignore the features and corrupt the filesystem. Newer U-Boot (2026-era) will refuse to write to the partition.

Now that I've got some free time… I had a look at the boot-loader for the TS-7670. I have an old port of U-boot from about 2017 or so… but that does not build with modern gcc, so I had a go at porting it.

No dice, it flatly refuses to boot… but I tried the `mx28evk` config: and *that* does… this is what I originally used for the TS-7670 port years ago, so maybe I need to circle back and have a look. Also Technologic Systems have got an official TS-7670 U-boot source tree too, so maybe I start bringing that up-to-date.

This is what I see on the console booting the `mx28evm` build of U-boot… sure doesn't find the SD card (probably because pin muxing is wrong), but it at least gives it a solid crack and does something.

```
HTLLCLLC

U-Boot 2026.04-00179-g5727c33705f1 (May 31 2026 - 19:30:14 +1000)

CPU: Freescale i.MX28 rev1.2 at 454 MHz
BOOT: SSP SD/MMC #0, 3V3
DRAM: 128 MiB
Core: 91 devices, 13 uclasses, devicetree: separate
NAND: 0 MiB
MMC: MXS MMC: 0
Loading Environment from MMC... MMC: no card present
*** Warning - No block device, using default environment

In: serial
Out: serial
Err: serial
Hit any key to stop autoboot: 0
MMC: no card present
MMC: no card present
Booting from net ...
Unknown command 'dhcp' - try 'help'
zimage: Bad magic!
```

#UBoot #iMX286 #Linux