RELENG_6: serial console drops back from 115200 to 9600 baud

[Ian Dowse]

In message <44010701.1050007 at andric.com>, Dimitry Andric writes:
>Okay, but why did 4.x through 5.x through 6.x (these have all been on
>this particular machine) always boot with 115200 until now? :)

They probably used 9600 for the boot blocks, and then switched to
115200 when /boot/loader started, so you didn't notice. Now the
settings from the boot blocks get used by /boot/loader.

>Anyway, I also thought that installworld would take care of installing
>any updated boot blocks, if necessary.  I'll manually install them and
>see what I end up with.

Boot blocks need to be installed manually - installworld installs
the boot blocks as files in /boot/boot{1,2}, but when booting, it
is the boot blocks in the first 8k of the slice that are used, not
the /boot/boot{1,2} files.

>Ah, but notice that I didn't use boot0sio, but the regular boot0.  It
>seems the serial port speed setting is compiled out in the latter
>version.  Hence the port speed will be the BIOS default, which I alas
>can't change; it's always 9600n1.

The boot blocks in question here are the ones installed inside the
slice (boot1 and boot2), rather than the boot0 MBR boot code, which
is installed in the very first sector of the disk. The boot0 boot
manager selects which slice to boot from, and then it invokes the
boot{1,2} blocks within the slice, they load /boot/loader and it
loads the kernel.

Ian