DDB over IPMI-sol

[da1]

Hi guys,

We have a 8-STABLE machine and while talking about it yesterday at work, the subject of DDB via IPMI-SOL came up. I did a quick search and came across 10.4 On-Line Kernel Debugging Using DDB handbook section. After reading it a couple of times, I realized that the first option ( the "-d" boot flag) doesn't apply to our needs (as the server is in the DC and we would need to go there) and the second option (to drop to DDB via

sysctl debug.kdb.enter=1

doesn't work over a SOL session. However, I saw this:

There is an option available for serial consoles that allows the use of a serial line BREAK on the console line to enter DDB (options BREAK_TO_DEBUGGER in the kernel config file). It is not the default since there are a lot of serial adapters around that gratuitously generate a BREAK condition, for example when pulling the cable.

This might be something we could use but I have a hard time understanding the BREAK concept and I'm not really sure that this will provide the functionality we require.

The idea is to have DDB access via IPMI-sol (if possible).

Any thoughts ?