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>