On Tue, 2016-10-25 at 15:59 -0400, Jarod Wilson wrote: > On Tue, Oct 25, 2016 at 02:14:08PM -0400, Don Zickus wrote: > > > > On Tue, Oct 25, 2016 at 10:46:00AM -0700, Laura Abbott wrote: > > > > > > The Fedora kernel has had roughly the same system for generating > > > the kernel configuration for a very long time. There are a series > > > of files listing configuration choices (CONFIG_FOO=y, CONFIG_FOO > > > is not set etc.) that get combined to generate the final config > > > files. This has gotten unsustainable for several reasons: > > > > > > - When the system was first introduced, the only supported > > > arches were x86_32 and x86_64. Fedora now supports enough > > > other arches that we have a config-$arch-generic in addition to > > > config-generic > > > - It's difficult to tell what is actually enabled since > > > there are several layers of configuration combining (I have to > > > look at config-generic, then config-$arch-generic, then > > > the final config-$specific file to see what the option actually > > > is) > > > - Keeping the files organized requires manual work and pruning > > > > > > I've been thinking about alternatives to the existing config > > > generation. One proposal was to take advantage of the upstream > > > kernel now supporting config fragments and keep some part of > > > the fedora configuration upstream. This would have the > > > disadvantage > > > of requiring the configuration to be kept in sync with upstream. > > > > > > Another option is to switch to a system of generation where > > > each configuration option is kept in a separate file. There > > > is no sorting or organization necessary. This would result > > > in a lot of small files for all the arches Fedora supports > > > though. > > > > Hi Laura, > > > > Just to throw it out there, RHEL has been using the one option per > > file > > mechanism for years now with success. Minimizes the maintenance > > and > > conflicts. ( I know you already know that, just wanted to publicly > > state > > that). > > > > The volume of files is large, but it is hidden away and you only > > package the > > resulting kernel.config files into the src.rpm. > > I'm quite fond of the was things were done in el7 too, but I'm > biased, > since I'm the one that implemented it. ;) > > Honestly though, part of the reason for doing it was because those > various > stacked config hunks were *terrible* to deal with in el6, and people > constantly touched the wrong one, had no idea how the end configs > were > actually compiled, etc., and I don't think anyone has ever gotten it > wrong > with the approach used now in el7. In the end, the srpm uses a merged > config for each kernel build/arch, so it's simple for people doing > their > own custom builds to modify the right config, and the git tree > heirarchy > still makes it pretty obvious what's enabled where -- the path from > single > files to kernel-foo.config is pretty straight-forward and obvious. I > don't > think I have anything bad to say about this approach, other than > "there > are a lot of files", and the most difficult part was the initial > conversion, making sure no end result config values differred from > the > prior method. What happens in RHEL7 if a kernel config option disappears (i.e. is eliminated from all Kconfig files)? I don't think I've ever hit that situation, so I honestly don't know. The reason I ask, of course, is that such a situation seems much more likely with Fedora kernels than with RHEL kernels, since the latter are ostensibly less tumultuous with features and options coming and going. The answer may be to simply sweep the config to eliminate unused options periodically, but it is worth stating that if so. John -- John W. Linville Hope is a good breakfast, but it is a linville@xxxxxxxxxx bad supper. -- Sir Francis Bacon _______________________________________________ kernel mailing list -- kernel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to kernel-leave@xxxxxxxxxxxxxxxxxxxxxxx
