On Fri, Aug 19, 2016 at 11:07:36AM +0200, Michal Marek wrote: > On 2016-08-18 19:55, Luis R. Rodriguez wrote: > > On Wed, Aug 17, 2016 at 09:26:58PM +0200, Cristina Moraru wrote: > > > >> This patchset implements dynamic pegging of kconfig symbol > >> into driver modinfo section > > > > First a little bit of motivation here helps, so let me try to > > help fill in some gaps. This may help explain what you have > > been working on a bit more. > > > > First, for those that were not Cc'd but curious about this work > > so far, you can read the patches here: > > > > Original cover letter: > > > > https://lkml.kernel.org/r/1471462023-119645-1-git-send-email-cristina.moraru09@xxxxxxxxx > > > > https://marc.info/?l=linux-kernel&m=147146213519750&w=2 - patch 1 > > https://marc.info/?l=linux-kernel&m=147146209019744&w=2 - patch 2 > > https://marc.info/?l=linux-kernel&m=147146211819747&w=2 - patch 3 > > https://marc.info/?l=linux-kernel&m=147146209119745&w=2 - patch 4 > > https://marc.info/?l=linux-kernel&m=147146209519746&w=2 - patch 5 > > > > There are a few situations in which you may want to extract a > > subset of Kconfig CONFIG_* symbols for a system. At least when > > only considering modules: > > > > a) When optimizing build requirements for a kernel for a system. > > That is you boot into a distro kernel and then want to build > > a slim kernel only with sensible kernel configuration options. > > > > b) When you are on a distribution kernel but the distribution > > kernel provided lacks hardware support for your device, you > > may either want to upgrade the full kernel in which case you > > want to do a) or -- you may want to just a backports release > > which provides just the modules you need, you'd use it on top > > of the distribution kernel. > > c) Having the mapping in sysfs would allow to simplify > streamline_config.pl avoid parsing Makefiles in perl. Indeed, this was actually a side possible goal here :) only it seems we totally forgot about it while addressing the work. > Only if the patch did not depend on streamline_config.pl :) Indeed, lets get rid of that dependency. > One idea would be to generate > the Module.ksymb in a similar way we generate the modules.builtin file: > Generate an alternate include/config/*.conf with all CONFIG_FOO=m > replaced with > > CONFIG_FOO=m-CONFIG_FOO > > and in the Makefile, iterate over $(filter m-CONFIG_%, $(.VARIABLES)) to > create the mapping. This would also properly cover cases where we build > the $(obj-m) list from another list. It would certainly create other > corner cases, but it's worth trying IMO. Neat, would that cover lib-m then as well or other targets that would generate modules ? > Another thing is that we do not necessarily need to record this > information in .modinfo, but we can generate a list in > /lib/modules/`uname -r`/ for consumption. It could also include drivers > that are builtin in the current configuration. Well so one future use would be for instance a 'make udevconfig' which in theory should be able then to scrape all possible related needed device CONFIG_'s and then give you an optimal kernel configuration. It'd be nice to be able to extract this from the kernel and modules without needing build sources in /lib/modules/`uname -r`/. Thoughts? Luis -- To unsubscribe from this list: send the line "unsubscribe backports" in
