[coreboot] SeaBIOS wit USB3.0 hub and USB3.0 devide behind the hub

[Werner Zeh]

Hi all.

I have made some tests with SeaBIOS and XHCI and found, that on my board (which is baytrail-based)
a USB3.0 hub won't work. For those who are familar with SeaBIOS I have attached two
logfiles from SeaBIOS. One of them is with the USB3.0 flash drive directly connected to one of the root ports of SoC
(in which case the boot process starts from the flash drive) and the other is with the same flash drive but a USB3.0 hub in between 
(I have used a hub from Delock #62534, http://www.delock.de/produkte/F_247_extern_62534/merkmale.html). In the hub-case, I see the
"No bootable device" screen and no boot will happen.

Maybe someone more experienced can see the cause from the logs.

Werner