The sparc install document should mention that if you are doing
the install over a serial port (ttya) the baud rate should be set
at both the PROM monitor (using setenv ttyxxx command) and the users's
terminal (emulator) BEFORE net booting (and I assume BEFORE
a floppy install also).

I have verified the following behaviour using the net boot on 1.5,
starting at a baud rate of 38400:

ok boot net netbsd
....
(c) and all probe messages ok....
....
erase ^H, werase ^W, kill ^U, intr ^C
xxx...|x..|xxx.x.x..x

At this point the install program switches to 9600 baud, and the install
doesn't look promising because of the garbage on the screen.  Also note
that a character transmited at 1/4 or less than the receive's baud rate
(perhaps due to the user's randomly trying different baud rates, if they
are smart enough to know to try this) triggers the BREAK detection on the
rs232 receiver circuit, which the sparc PROM interprets as the L1/stop key
which then drops into the PROM prompt, also not looking promising.  Of 
course because of the i/o baud rate mismatch, the ok prompt is garbled.
When they eventually get the right baud rate, they see ok instead of
I)nstall, etc..., since they have crashed their machine.

Advanced users would know to type 'go' to get the I)nstall, etc., prompt.

Note also that if you made it through the install by changing the baud rate
after the probe messages, once you type halt, the baud rate reverts back to
the original value in the PROM (38400 in my case), boots the system with
garbage on the console until you change the baud rate back from 9600 to 38400.

If you somehow suffer through the garbage and get a login: prompt (also in
gibberish), but press return, you will again cause the L1/stop effect and
crash your system.

There are 2 solutions
~~~~~~~~~~~~~~~~~~~~~
1.  Remove the part of sysinst (or whatever) that changes the baud rate to
    9600.

2.  Put instructions in the install document that user's set their terminal's
    baud rate and the PROM baud rate (for the PROM monitor and probe part) to
    9600 when installing over a serial port.

I mentioned this a few years ago, too, but can't find it in the archive.