OpenSolaris

Headsup: usb serial console support on x86

Date: Wed, 14 Jun 2006 09:06:44 -0700 (PDT)
From: Shudong Zhou <szhou at billybob dot sfbay dot sun dot com>
To: on-all at sun dot com, onnv-gate at onnv dot eng dot sun dot com
Subject: Headsup: usb serial console support on x86

With the putback for
   6426010 Need ability to direct console to USB serial device
you may direct Solaris x86 console to a usb serial device (useful
for laptops without built-in serial connector). The functionality
is not documented for end users, due to the lack of BIOS and
early boot support.

To enable it, run
    # eeprom console=usb-serial
and reboot. Or, edit the GRUB menu to have
    kernel ... -B console=usb-serial

Here are a few things to know with usb serial console.
    - Runtime kmdb (mdb -K) is available, but boottime kmdb isn't.
    - kmdb depends on polled I/O, which works for uhci+usbsprl.
      Support for other devices will come later.
    - Output is available after kernel driver attaches.
      Early boot messages are saved in a buffer and flushed
      when console is available.

Comments and suggestions are welcome.
Shudong