The USB2 companion hub carrying the user's full-speed keyboard never
appears — only the SuperSpeed hub (port 19) and SS storage (port 21)
connect. To find where the USB2 root ports are and whether the companion
is presenting on one, walk the xECP Supported Protocol capabilities
(logging each USB 2.0 / 3.0 root-port range) and dump every port's raw
PORTSC unconditionally (ccs/ped/pls/pp/speed). QEMU confirms the dump
(USB2 ports 5-8, USB3 ports 1-4). Branch-only diagnostic.
Daniel Samson
10956c6660