custom kernel, make buildkernel and then?

Erik Norgaard norgaard at
Wed Oct 11 00:56:26 PDT 2006

Zbigniew Szalbot wrote:
> Hello,
> Hope you can advise me. I have a FreeBSD 6.1 stable system for which I 
> want to build a custom kernel. However, I am scared to death (almost ;) 
> and just want to make sure I have it done the right way.
> I have in the past used supfile with ports-all option and couldn't build 
> a custom kernel. Yesterday it dawned on me that I need sources for that, 
> not ports. So I ran cvsup with src-all option. Now, I followed these steps:
> # cd /usr/src/sys/i386/conf
> # mkdir /root/kernels
> # cp GENERIC /root/kernels/LISTS
> # ln -s /root/kernels/LISTS
> then I used procedure 2 for building the kernel the new way.
> # cd /usr/src
> # make buildkernel KERNCONF=LISTS
> It all went well without any complaint (I was really puzzled - when it 
> comes to IT, I usually see half-empty glasses...) but now I wonder. My 
> next step is supposed to be make installkernel KERNCONF=LISTS
> Is it OK to do it on an already configured system? I have some usual 
> applications like php, mysql, apache, exim MTA configured and working. 
> So in other words I am trying to build a custom kernel not on a fresh 
> install but on an already working system (operating for 25 days). It is 
> not a webserver but it is running and needs these apps. My fear is that 
> I am likely to break something.

Yes, you can install the kernel. Applications don't live in kernelspace. 
If your kernel fails to boot you can boot the old kernel by in the 
loader menu go to a promt, unload the kernel and load kernel.old.

I usually build a GENERIC kernel and copy it with modules to 
/boot/kernel.GENERIC - just as my custom kernel is copied to 
/boot/kernel.CUSTOM as the kernel.old is overwritten on every install.

You might in some limited cases experience problems if you updated and 
build/install world, but that's a different story.

> Will shutdown -r now be enough? Or do I have to boot in single user mode?

Just reboot as normally.

Cheers, Erik

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