Kernel exploration via FreeBSD Kernel Internals: An Intensive Code Walkthrough, by McKusick

decuser

decuser

I would like to set up a VM to work through the McKusick videos and material. Reading code and talking through it is great, but I really want to be able to tweak bits and see my changes in action. Since the release is available online, I know that I can download pretty much ISO or vm of the version 11 system. I downloaded the 11.0 release that was put out in September 2016 (the book is based on a version from June, but I'm not sure which and figure the release is close enough). I think I want to install the 11.0 as released (rather than 11.2) just to be sure that what I'm looking at hasn't drifted from what is presented in the video/book. My thinking is that if I have an unpatched 11.0 version running in a vm with the source, I can tweak and build and get expected results based on the video talks. My challenge is that pkg isn't installed and if I use pkg to install stuff, it will try to download stuff.

Is it reasonable to set up 11.0 on a vm without internet access and install stuff straight from the DVD?

Thanks,
Will
 
Thought about this a bit more and decided that I was going about it in a convoluted manner. Solution:

Install 11.0 in VM and install src
pkg update && pkg upgrade as per usual (this doesn't update the src, doh)
cp -R /boot/kernel/kernel /boot/kernel/GENERIC
cd /usr/src
tweak kernel source as desired
make -j8 buildkernel
install kernel if you dare
boot GENERIC if stuff breaks
etc...
 
With these tasks it doesn't really matter what version you're going to use, what does matter is understanding the underlying mechanics.

As to your kernel issue: just copy your default GENERIC kernel into the /boot/kernel.gen directory. Then add this to /boot/loader.conf:
Code: 
kernels="kernel kernel.old kernel.gen"
This will make sure that your boot menu will always provide you with 3 kernels to boot from. And since the normal installation process only uses /boot/kernel and /boot/kernel.old you'll always have a backup no matter how badly you mess up.
 
I've gone through a few iterations and I have a much better understanding thanks to the comments y'all have provided. Crashed a kernel, booted from the backup version, restored a working copy, etc.
 
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