Supermicro + IPMI + FreeBSD: Kernel prints at 1-bps

Solution 1:

If anyone can explain why this happens, please post your own answer. If you answer is good, I'll accept your answer over mine.

The quick and easy solution, choose the other COM port. Apparently I had a mismatch between COM A, COM B, which are called 03F8 and 02F8 in other places. The BIOS was configured to use COM A. The FreeBSD bootloader settled on some sane defaults, which is why the bootloader behaved fine. The FreeBSD kernel were expecting to see COM B. COM A was unconfigured in the Operating System, and thus the kernel settled on some strange defaults (1 bps). The bps rate of the serial console also affects the speed of text printed to the video console.

Keep in mind that I wasn't using the serial console, but we always configure the serial consoles on our systems so that IPMI's Serial-over-LAN (SOL) works, as some of the sysadmins here prefer SOL.

I swear I tried this before and it didn't work. But now, it works.

It might also be possible to prevent this by twiddling with uart settings in /boot/device.hints .