RELENG_6: serial console drops back from 115200 to 9600 baud

Ian Dowse iedowse at
Mon Mar 6 21:21:22 UTC 2006

In message <F62095EB-C244-4128-8FAA-41AC29D3FCF2 at>, Vivek Khera writes
>On Feb 27, 2006, at 12:29 PM, Ed Maste wrote:
>I'm not having any luck getting my 115200 baud serial console back.   
>The machine was upgraded from 5.4-STABLE to 6.1-PRE last week, and  
>again over the weekend.  I did the following:
>make buildworld and buildkernel with BOOT_COMCONSOLE_SPEED=115200 in / 
>etc/make.conf, options CONSPEED=115200 in the kernel config.
>make installkernel, reboot, yada yada yada, installworld,.. then  
>boot0cfg -B aacd0 to update the boot blocks.
>Now, at this point I expected to have a 115200 console on the next  
>boot.  Nope. Got 9600 baud again.

There are a lot of steps to the boot process so it can be confusing
- the command you wanted was disklabel, not boot0cfg. The boot0cfg
program installs boot0, which is a 512-byte boot manager that you
can optionally install in the MBR to give a menu of slices to boot
from - it has nothing to do with reading /boot.config and doesn't
set up the serial port.

If the slice you boot from is aacd0s2 then you can use `disklabel
-B aacd0s2' to install the new boot blocks (boot1 and boot2)
into that slice.

>The other side-effect is now I get this stupid "Boot F1 for DOS and  
>F2 for FreeBSD" menu which defaults to DOS (which is the Dell utility  
>partition).  How do I get back to the original boot style where it  
>just boots freebsd without any menu?

That's boot0. `fdisk -B /dev/aacd0' should put back the basic MBR.

>So I updated my /boot.config to read:
>  -Dh -S115200
>now on boot, the boot0 drops to the prompt and makes me type in "/ 
>boot/loader" to continue the process.  It is as if it forgot what  
>file to load, and ignores the -S option anyhow, because I still end  
>up with a 9600 baud console.

Presumably the boot loader (boot1/2) drops you at the prompt because
it is old and does not understand the "-S115200". Once you update
the boot blocks with disklabel, that /boot.config should work.


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