Re: 答复: 答复: 答复: Getting Started with freebios2!

Steven James  writes:
> For the serial, UHCI and OHCI will be good. EHCI can likely be ignored for
> the BIOS since fast devices are required to fall back and EHCI always has
> one of UHCI or OHCI to handle low speed USB.

Actually not.  At least not for serial before the memory is initialized.

For early serial only EHCI is an option.  The EHCI debug port can be used
with just I/O to the EHCI, no DMA is require.  OHCI, UHCI, and normal
EHCI require DMA transfers so they are not an option.

Eric