Re: [gentoo-user] Upgrading old kernel

[Thomas Mueller]

On 4/15/20 1:40 PM, Andreas Stiasny wrote:
> On 15.04.20 17:50, Rich Freeman wrote:
 
>> Jumping from
>> 3.18 you're somewhat more likely to run into issues - your biggest
>> headache though will be dealing with the 30,000 prompts you get from
>> make oldconfig and making sure you set all the new options correctly.
 
> That's why I use make olddefconfig in such a case. This takes all the
> old config values and uses the default for the new ones. If you know
> that you need one or more of the new config options you can fine tune
> them afterwards with make menuconfig.
 
 
> Andreas

james responded:

> Ah. never used olddefconfig, I'll give it a spin.

That raises the question, what if you have no kernel config, as may be the case if you are going to Gentoo for the first time, or are cross-compiling from FreeBSD or NetBSD?

I have tried with OpenADK (www.openadk.org), which got as far as successfully building cross-gcc some of the time, but never succeeded at building the kernel.

Is defconfig the best starting point?  One would want to maximize the probability of success building the kernel while retaining a functional system that would support vital hardware including ethernet, wi-fi, hard drives and USB, and I would need to be able to read a NetBSD or FreeBSD file system (UFS/FFSv1 or 2).  I use GPT, so there are no traditional now-deprecated BSD disklabels that Linux would not recognize.

If I just start with menuconfig, I could miss some vital parts.

OpenADK started with a minimal kernel config, maybe it was too minimal?

I have successfully compiled kernels and userlands on FreeBSD and NetBSD (no menuconfig, defconfig, etc; kernel configs start with a GENERIC config).  NetBSD kernel config is much longer than FreeBSD kernel config but is dwarfed by Linux kernel config.

Tom