On 2016-08-23 23:32, Luis R. Rodriguez wrote: > 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 should be obj-m-CONFIG_% >> 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 ? This would have to be handled as well by the patch. Obviously it's not going to be as simple as described in a single paragraph of text :). >> 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`/. I meant that the file can be installed by modules_install. Like you have /lib/modules/`uname -r`/modules.builtin with recent kernels and recent distro packages. But really, it's a minor issue how the information is presented to userspace. Michal -- To unsubscribe from this list: send the line "unsubscribe backports" in
