No keyboard while in loader, HP Proliant DL120G6

[dorjechang]

Trying to install a new server, HP Proliant DL120G6. Trying PS/2 and USB keyboards. Both work well in BIOS and after the kernel boot. But both do not work while in loader.
I've tried 13.4-RELEASE and 14.2-RELEASE with the same result.

Any advice?