Comment 51 for bug 1244176

Note that while this particular bug, about missing ohci-pci in the initramfs, is fixed in Ubuntu 15.04 another similar bug, missing xhci-pci, is still present. The debian bug report about, and fix for, missing xhci-pci is here: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=773250

If you are experiencing these symptoms on Ubuntu 15.04 (USB keyboard working in installed and Live systems, but not debian-installer / early boot initramfs), you are probably hitting the xhci-pci bug.