On Mon, 9 Mar 2009, Alain Kalker wrote: > Martin has an older version of the drivers packaged for building with > DKMS on Ubuntu in his PPA[5], but it currently has some disadvantages: > > A. It builds all available drivers, no matter which hardware is actually > installed in the system. This takes a lot of time, and may not be > practical at all on systems with limited resources (e.g. embedded, MIDs, > netbooks) > B. It currently has no support for Jockey to detect installed hardware, > so individual drivers can be selected. > > To address these issues, I would like to propose the following: > > A. Building individual drivers (i.e. sets of modules which constitute a > fully-functional driver), without having to manually configure them > using "make menuconfig" > > I see two possibilities for realizing this: > Firstly: generating a .config with just one config variable for the > requested driver set to 'm' merged with the config for the kernel being > built for, and then doing a "make silentoldconfig". Big disatvantage is > that full kernel source is required for the 'silentoldconfig' target to > be available. Does that actually work? Figuring out that needs to be turned on to enable some config options is a hard problem. It's not just simple dependencies between modules, but complex expressions that need to be satisfied. E.g., something "depends on A || B", which do you turn on, A or B? There are multiple solutions so how does the code decide which is best? > Secondly, the script v4l/scripts/analyze_build.pl generates a list of > modules that will get built for each Kconfig variable selected, but it > currently has no way of determing all the module dependencies that make > up a fully functional driver. I just wrote analyze_build.pl to make it easier for developers to figure out that source files make up a module and how to enable it. It's not actually used by the build system. It's also not perfect when it comes to parsing makefiles, i.e. it no where near a re-implementation of make's parser in perl. It understands the typical syntax used by the kernel makefiles but sometimes there is some unusual bit of make code that it won't parse. > The script v4l/scripts/check_deps.pl tries to discover dependencies > between Kconfig variables, but it currently is somewhat slow, and hase a > few other problems. That it is! It's not totally perfect either. Sometimes a driver will only depend on another if something is turned on. But the way check_deps.pl works won't know that. There are also lots of Kconfig variables that don't turn on a module but instead modify what a module does or are used for menus. I think a better system would be use the dependencies in the Kconfig files instead of trying to figure them out from the source. > B. To enable hardware autodetection before installing drivers, we need > to have a list of modaliases of all supported hardware. This may be the > hardest part, because many VendorIDs and ProductIDs are scattered > throughout the code. Also coldbooting/warmbooting hardware is a problem. Extract that from the compiled modules should be easy. -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
