I'm not sure any of this got pulled up to a release branch (i.e. 1.5.2) but
I enabled serial boot installs for x86 a while back. A snapshot should include
floppy images with serial boot blocks and a question midway through to ask
which set of blocks to install on the end machine.

James

>
>On Sat, 22 Sep 2001, Tommy Moore wrote:
>
>> Hi guys. I'm trying to install NetBSD on to a pentium class machine over
>> serial console using a null modem cable and terminal program on the
>> otherend.
>
>It would help if you had a floppy with the serial boot blocks. I've
>placed an image of one up on
>
>   ftp://ftp.netbsd.org/pub/NetBSD/misc/fredb/boot_com0.fs.gz
>
>This is not the install floppy, but only an empty file system with the
>serial boot blocks installed. You make it the same way as you'd make
>the two floppies from boot1.fs.gz and boot2.fs.gz. [I zeroed it out
>first so it would compress well, so I wouldn't want to put up a
>non-gzipped version.] Once it sends the banner over the serial port
>(com1 on the target, 9600bps, 8-N-1), you have about 10 seconds to hit
>the space bar and catch the boot prompt. (Actually, if you miss, it
>might simply return to the prompt once fails to find a kernel.)
>
>Once you get the prompt, swap in the first installboot floppy, and
>type:
>
>   boot fd0a:netbsd
>
>Proceed as usual. Once you're done installing, you can install the
>serial boot blocks to the hard drive before you even let it reboot.
>Choose "Utility Menu"; choose "Escape to Shell", and at the shell
>prompt, type
>
>   mount /dev/wd0a /mnt
>   /mnt/usr/mdec/installboot /mnt/usr/mdec/biosboot_com0.sym /dev/rwd0a
>   umount /mnt
>
>If you forget, or something goes wrong, you can just use the serial
>boot floppy again, but type
>
>   boot wd0a:netbsd
>
>Let us know how it goes.
>
>Frederick
>
>
>
>
>