Since this a kernel debugging scenario I normally build a kernel with:
CONFIG_USB_SERIAL_CONSOLE=y CONFIG_USB_SERIAL=y CONFIG_USB_SERIAL_PL2303=y (or whatever is the relevant driver)
..to make this work at boot time with the kernel.
Since this a kernel debugging scenario I normally build a kernel with:
CONFIG_ USB_SERIAL_ CONSOLE= y USB_SERIAL_ PL2303= y (or whatever is the relevant driver)
CONFIG_USB_SERIAL=y
CONFIG_
..to make this work at boot time with the kernel.