Hi jernst,
Please do “scsi reset” under u-boot to check if your SATA drive can be detected, then do ext4ls to list the file system of your SATA partition. To setup boot from SATA drive is very similar to boot from SD card, except to use scsi instead of mmc as the parameter to the ext4load. We’ll try to get the instructions on the ESPRESSObin wiki, before it is ready, please check the doc at http://wiki.macchiatobin.net/tiki-index.php?page=Use+SATA+drives+in+U-Boot for reference.
Below are the examples for scsi reset and ext4ls
Marvell>> scsi reset
Reset SCSI
Setting SCSI to 0
Target spinup took 0 ms.
AHCI 0001.0300 32 slots 1 ports 6 Gbps 0x1 impl SATA mode
flags: ncq led only pmp fbss pio slum part sxs
scanning bus 0 for devices…
Device 0: (0:0) Vendor: ATA Prod.: PNY CS1311 120GB Rev: CS13
Type: Hard Disk
Capacity: 114473.4 MB = 111.7 GB (234441648 x 512)
Invalid port number 2
Invalid port number 3
Invalid port number 4
Invalid port number 5
Invalid port number 6
Invalid port number 7
Found 1 device(s).
Marvell>> ext4ls scsi 0:1 /
4096 .
4096 ..
16384 lost+found
4096 bin
4096 boot
4096 dev
4096 etc
4096 home
4096 lib
4096 media
4096 mnt
4096 opt
4096 proc
4096 root
4096 run
4096 sbin
4096 srv
4096 sys
4096 tmp
4096 usr
4096 var
Marvell>>