From Jeff Wiedemeier:

How about this.. This version no longer piggy backs on ttyS0 (it
actually doesn't touch any files outside arch/alpha/kernel at all). It
does use a dynamic major for the tty piece of the driver. From
userspace, /dev/console is ok for most uses, but because of the 'noctty
= 1' at tty_tio.c:1329 (in the IS_SYSCONS_DEV section) using
/dev/console cannot result in a controlling tty so some things, like
'resize' and bash job control don't work. For those uses, however, it's
easy enough to parse /proc/devices on the way up to get the major number
and create the specific device for the tty side of the driver.

I made a distinction in kernel options as well. "srmcons" specifically
requests the early prints (as before) and "console=srm" requests the
full driver, including the early prints. The two options can be
combined with "console=srm" behavior resulting. The other change is that
if "console=srm" is specified, I don't unregister_srm_console before
console_init any more - that only happens in the "srmcons" case. That
way preferred console selection remains stable and "console=srm" doesn't
result in the early messages being repeated when the driver
re-registers. The use of "srmcons_allowed" is also eliminated due to the
"srmcons" vs. "console=srm" distinction.