Andrew, All, On Tuesday 16 July 2013 09:56:11 Andrew Morton wrote: > On Tue, 16 Jul 2013 00:47:27 -0700 Andrew Morton <a...@linux-foundation.org> > wrote: > > On Mon, 15 Jul 2013 15:08:20 -0700 "H. Peter Anvin" <h...@zytor.com> wrote: > > > On 07/15/2013 03:03 PM, Andrew Morton wrote: [--SNIP--] > > > We keep running over the need to be able to have kconfig run tests on > > > the build system (for toolchain support or for optional tools needed); > > > running them in the Makefiles (i.e. at Kbuild time) is simply too late. > > > > > > > Would it make sense to extend Kconfig's `depends'? > > > > depends on $(shell-command) > > > > I don't know how practical that would be to implement...
I'm afraid this will get rather ugly and not trivial. Can we mix 'depends on SYMBOL' and 'depends on $(command)' ? Can we mix both in a boolean expression such as 'depends on SYMBOL && $(command)' ? What would be the condition for evaluating the dependency rule? Evaluation at Kconfig read-time might not be enough, given this construct: config FOO depends on $(foo) comment "'foo' is missing, please install it" depends on !$(foo) Also, I believe Kconfig should stay a config-only language, without much esoteric features. > Or, easier and faster, run some front-end script which generates > once-off Kconfig symbols. > > if [ -x /bin/lz4c ] > then > echo CONFIG_HAVE_LZ4C > fi > > then munge the output of that script into the Kconfig run and do > > depends on HAVE_LZ4C Yes, this is a better solution. For what it's worth, this is what I'm doing in crosstool-NG: a script checks for optional pre-requisites, spits out a Kconfig blob which is included by the top-level Kconfig file. Here is a snippet of generated Kconfig blob: config HAVE_XZ def_bool y config HAVE_LZMA bool Which means we do have 'xz', but not 'lzma'. This is relatively trivial to do, so I'll tackle this this evening when I'm back home (unless someone beats me to it). Regards, Yann E. MORIN. -- .-----------------.--------------------.------------------.--------------------. | Yann E. MORIN | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: | | +0/33 662376056 | Software Designer | \ / CAMPAIGN | ^ | | --==< O_o >==-- '------------.-------: X AGAINST | /e\ There is no | | http://ymorin.is-a-geek.org/ | (*_*) | / \ HTML MAIL | """ conspiracy. | '------------------------------'-------'------------------'--------------------' -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/