On 10/11/2011 07:51 PM, Khem Raj wrote: > On Tue, Oct 11, 2011 at 3:15 PM, Richard Purdie > <richard.pur...@linuxfoundation.org> wrote: >> On Mon, 2011-10-10 at 11:41 -0700, Darren Hart wrote: >>> As part of working on meta-tiny, I've come across a need (want?) to >>> present users with the ability to select some set of features in a local >>> configuration file that will impact the build of the image and a set of >>> recipes. >>> >>> It is currently possible to affect which packages are installed in an >>> image with variables like POKY_EXTRA_INSTALL. What I'm not finding a way >>> to do is specify some set of features that will impact how a recipe is >>> built. >>> >>> For example, a user may or may not want networking support or virtual >>> terminal support in their image. This impacts both the kernel and >>> busybox (at least). The linux-yocto infrastructure provides us with >>> config fragment functionality, something similar will need to be added >>> to busybox. Access to that is still bound to the machine config by means >>> of the SRC_URI machine override mechanism, but it would be useful to be >>> able to influence it from the image config or the user's local config. >>> >>> For example, when building a tiny image I may decide I do not want VT >>> nor INET support. I might wish to specify this like this (by removing >>> them from the default features): >>> >>> local.conf: >>> #CORE_IMAGE_TINY_FEATURES = "VT INET MDEV" >>> CORE_IMAGE_TINY_FEATURES = "MDEV" >>> >>> I would want this to affect linux-yocto-tiny by dropping the vt.cfg and >>> inet.cfg fragments from the SRC_URI (or from the .scc descriptor files >>> assembled by the linux-yocto meta indrastructure). >>> >>> Busybox would need a similar configuration mechanism, and would also >>> need to add a "no-vt-support.patch" patch to the SRC_URI to avoid a >>> bug/oversight in the busybox init routine. >>> >>> I'd appreciate some help determining the proper bitbake way of doing >>> this. I want to avoid having to create a new machine.conf and/or recipes >>> for every possible combination of features that a user may want to turn >>> on or off. >> >> We have a few mechanisms around for this but its a difficult problem to >> do totally generically since everyone has their own ideas about what >> should/shouldn't happen. >> >> One tricky aspect is that some people care about package feeds and the >> output into those needs to be deterministic. This is why DISTRO_FEATURES >> exist which state things like "does x11 make sense"? This means dbus may >> or may not be compiled with X but given a set of policy decisions by the >> distro, the output is determined. >> >> Recently we've taken the idea of PACKAGECONFIG on board. This is recipe >> level policy which can enable/disable features in a given recipe (e.g. >> does gsteamer depend on and build flac or not?). Whilst we have a high >> level setup for this for autotools recipes, this is probably something >> we need to do a more custom implementation of for busybox and the >> features you mention above would map well to this. It would be good to >> have a standardised way of representing this (and we may also want to >> look at moving the kernel feature control towards this variable name >> too). >> >> What we need to be really really careful about is getting the >> namespacing right and your CORE_IMAGE_TINY_FEATURES = "VT INET MDEV" >> example above scares me as it mixes up several different things. My >> worry is for example trying to build two different versions of busybox >> in the same tmpdir depending on what image you build, for example what >> does "bitbake core-image-tiny core-image-sato" do? >> >> Contrast this to some settings: >> >> PACKAGECONFIG_pn-linux-yocto = "vt inet" >> PACKAGECONFIG_pn-busybox = "mdev" >> >> which then mean you have one set of configuration for these recipes and >> its clear what the bitbake command above would result in. >> >> One of the bigger problems we're going to have with tiny is its >> effectively a different set of distro settings to our normal builds. The >> side effect of that is that you couldn't share a tmpdir with a "big" >> build but I'm not sure that is an issue in practise, we just need to do >> it in a way which doesn't give us the nasty configuration corner cases. >> >> So I guess what I'm saying is the end result of your work is likely a >> "poky-tiny" distro setting which would take the "poky" distro but tweak >> some pieces for really small images. It would need a separate tmpdir and >> we should look in the PACKAGECONFIG variable direction for handling >> recipe specific customisations... >> > > FWIW I agree it seems like a new distro to me. I think if we add more to mix > it just will complicate the customizations and may even make it > difficult to share > things.
Along the same line of thought, does this overlap with the micro distro? Philip _______________________________________________ yocto mailing list yocto@yoctoproject.org https://lists.yoctoproject.org/listinfo/yocto
