In the end it was (again) a messy u-boot config. Just in case anybody gets ever again a similar problem, I just add my current enviroment:<div><br></div><div><div>baudrate=115200 </div>
<div>ethaddr=... </div>
<div>eth1addr=...</div><div>ethact=egiga0 </div>
<div>x_bootcmd_kernel=nand read.e 0x6400000 0x100000 0x400000 </div>
<div>x_bootcmd_ethernet1=set ethact egiga1 </div>
<div>x_bootcmd_ethernet=ping 192.168.2.1 </div>
<div>bootcmd=run x_bootcmd </div>
<div>bootdelay=5 </div>
<div>arcNumber=0xa29 </div>
<div>mainlineLinux=yes </div>
<div>filesize=348858 </div>
<div>fileaddr=6400000 </div>
<div>gatewayip=E.F.G.H </div>
<div>ipaddr=A.B.C.D </div>
<div>serverip=E.F.G.H</div><div>bootargs=rootwait </div>
<div>x_bootargs=console=ttyS0,115200 </div>
<div>x_bootargs_root=ubi.mtd=2 root=ubi0:rootfs rootfstype=ubifs </div>
<div>x_bootcmd_usb=usb start </div>
<div>x_bootcmd=$(x_bootcmd_usb); $(x_bootcmd_kernel); setenv bootargs $(x_bootargs) $(x_bootargs_root) ;bootm 0x6400000; </div>
<div>stdin=serial </div>
<div>stdout=serial </div>
<div>stderr=serial </div>
<div> </div>
<div>Environment size: 693/131068 bytes </div></div>