as described here:
http://forum.odroid.com/viewtopic.php?f=95&t=15277#p116655

i'm having problems with usb attached 2,5" harddrives. the kernel reports:

Buffer I/O error on dev sda1, logical block 121667584, lost sync page write

i'm also seeing:

Nov 22 19:08:44 nixos systemd-journal[424]: Missed 219 kernel messages
Nov 22 19:08:44 nixos kernel: Emergency Thaw on mmcblk0p2

see the forum post for more information on my configuration, kernel config, u-boot version and bug-report!

thanks for the effort in porting xu4 support into kernel 4.2.0!