在Intel IXP 42X and IXC1100 Hardware Design Guideline中，
High Speed UART有一段是寫到，


For Mbaud signals, options are provided for pull up so that 1-Mbps transmission rate is
achieved, or pull down so that 250 Kbps transmission rate can be set. The default
setting is 1 Mbps. To allow full modem control on the fast UART connection, system
designers have to use four GPIO pins to generate the RS-232 signals (DTR, DSR, RI,
and DCD) that are not available on the processor high-speed UART interfaces.

可是他寫的Mbaud用pull up或是pull down去做設定，
但是IXP42X或是IXC都沒有看到有這個Pin可以去config，
在Developer's Manual中也只有靠Register config 1200baud up to 921Kbaud，
不知道板上有沒有前輩知道這個Mbaud是怎麼去config出來的呢？
謝謝！