FreeBSD and Multiple kernels

[bandwidth_pig]

Is it possible to have multiple kernels on FreeBSD as I do GNU/Linux? I have a stand alone BSD box and am in the process of recompling my kernel. Just curious.

[Alex Cavnar, aka alc6379]

Actually, you can.

You can copy your current running kernel to another name, and boot from that if you need to:


cp /kernel /kernel.runsgood


And, when you use make installkernel to install a new kernel, it always writes it to /kernel, and it moves the previous kernel to /kernel.old . Knowing these two items allows you to have multiple kernels. Before the system boots, you're given 10 seconds to hit <Enter> or any other key. If you hit any other key than <Enter>, you get a prompt. From that prompt, you can enter these commands:


unload
load /my_kernel_name_goes_here
boot


unload unloads the kernel loaded by the bootloader. Then, you issue a load command to boot your kernel. After that, boot will resume the booting process, using your chosen kernel.

[bandwidth_pig]

Thank you Alex.

[j79zlr]

watch out though, if you are building world along with a new kernel, e.g. a 4.9-RELEASE kernel might not like a 4.9-STABLE world.

[JohnT]

Originally posted by j79zlr
watch out though, if you are building world along with a new kernel, e.g. a 4.9-RELEASE kernel might not like a 4.9-STABLE world.


Thats the problem now days...no one it seems likes a stable world:p