On Fri, Oct 21, 2016 at 12:22 PM, Alexander Kapshuk <alexander.kaps...@gmail.com> wrote: > On Fri, Oct 21, 2016 at 6:42 PM, Andy Mender <andymenderu...@gmail.com> wrote: > >> Would a Gentoo .config work with the upstream "vanilla" 4.4.26 kernel? >> I know Gentoo does some patching to the upstream sources and menuconfig has >> additional features thereby. > > Running 'make oldconfig' within the sources directory by default uses > whatever config-x.y.z is the highest version available in /boot. > Otherwise, copying the config file desired to the sources directory > followed by running 'make oldconfig' will generate a new one based on > the config file copied. > You could than run the diff on the gentoo config file and the vanilla > one and take it from there.
Correct. I'm pretty confident (having done this a bunch of times) that it is just going to drop any config items it doesn't recognize including the Gentoo ones (removal of config items is normal anyway). Since the Gentoo ones just pull in other pre-reqs, and the way the config file works is that the pre-reqs also get written into the config file, you'll still have all the settings that actually matter. For example, systemd support probably turns on multiple pts support, and even if you get rid of the gentoo systemd option the multiple pts support option will remain selected. So, if you're staying in the same kernel series (4.4) you should just be able to run make oldconfig and that's it. You can take a look but I'd be shocked if you're either prompted for any new settings or if anything doesn't work exactly as before. You might just be missing a random patch or two (gentoo-sources doesn't have that many of them). Going between kernel series is going to be the same as always, you'll be asked a dozen questions for new options. Now, the one thing you'll lose without the Gentoo options is that if an openrc/systemd/udev/whatever requirement changes it won't just automatically get pulled in. You'll need to find out about it and manually update your config. Honestly, I think that option wouldn't be a bad one to merge upstream, though it obviously does cross the userspace/kernelspace boundary. Also, having end-users manipulate kernel config options is something very few distros do these days, I'm not sure if any of the well-known distros encourage it. -- Rich
