Re: [kbuild-all] make[2]: *** No rule to make target 'tools/testing/nvdimm//config_check.o', needed by 'tools/testing/nvdimm//dax.o'.

[Fengguang Wu]

On Tue, Aug 16, 2016 at 09:47:52AM +0800, Yilong Ren wrote:
> On Tue, Aug 16, 2016 at 09:41:02AM +0800, Fengguang Wu wrote:
> > On Mon, Aug 15, 2016 at 06:30:48PM -0700, Dan Williams wrote:
> > >On Mon, Aug 15, 2016 at 6:26 PM, Fengguang Wu <fengguang.wu@xxxxxxxxx> wrote:
> > >>On Mon, Aug 15, 2016 at 05:58:36PM -0700, Dan Williams wrote:
> > >>>
> > >>>On Mon, Aug 15, 2016 at 3:03 AM, kbuild test robot
> > >>><fengguang.wu@xxxxxxxxx> wrote:
> > >>>>
> > >>>>tree:
> > >>>>https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > >>>>head:   694d0d0bb2030d2e36df73e2d23d5770511dbc8d
> > >>>>commit: ab68f26221366f92611650e8470e6a926801c7d4 /dev/dax, pmem: direct
> > >>>>access to persistent memory
> > >>>>date:   3 months ago
> > >>>>config: i386-randconfig-i1-201633 (attached as .config)
> > >>>>compiler: gcc-4.8 (Debian 4.8.4-1) 4.8.4
> > >>>>reproduce:
> > >>>>        git checkout ab68f26221366f92611650e8470e6a926801c7d4
> > >>>>        # save the attached .config to linux build tree
> > >>>>        make ARCH=i386
> > >>>>
> > >>>>All errors (new ones prefixed by >>):
> > >>>>
> > >>>>>>make[2]: *** No rule to make target
> > >>>>>>'tools/testing/nvdimm//config_check.o', needed by
> > >>>>>>'tools/testing/nvdimm//dax.o'.
> > >>>>
> > >>>>   make[2]: Target '__build' not remade because of errors.
> > >>>
> > >>>
> > >>>I think this is an invalid build test.  tools/testing/nvdimm/ uses a
> > >>>external module Kbuild environment, not Kconfig.  So, there's nothing
> > >>>I can do to prevent this compile error, unless there's some other way
> > >>>0-day could determine the configuration dependencies?
> > >>
> > >>
> > >>Yeah if you can offer a concrete rule for the dependency, we'll add
> > >>it to 0-day.
> > >
> > >Sounds good.  The config_check.c file itself lists the dependencies:
> > >
> > >void check(void)
> > >{
> > >       /*
> > >        * These kconfig symbols must be set to "m" for nfit_test to
> >
> > If "y" is not a valid option, we'll need to adjust 0-day's dependency
> > specification for ndctl test:
> >
> > wfg /c/lkp-tests% cat include/ndctl
> > need_kconfig:
> > - CONFIG_HAVE_DMA_CONTIGUOUS=y
> > - CONFIG_CMA=y
> > - CONFIG_DMA_CMA=y
> > - CONFIG_CMA_SIZE_MBYTES=200
> > - CONFIG_LIBNVDIMM
> > - CONFIG_BLK_DEV_PMEM
> > - CONFIG_ND_BLK
> > - CONFIG_BTT=y
> > - CONFIG_NVDIMM_PFN=y
> > - CONFIG_NVDIMM_DAX=y
> > - CONFIG_ZONE_DEVICE=y
> >
> > In the above list, a bare "CONFIG_BLK_DEV_PMEM" means "y" or "m" are
> > both acceptable.
>
> Yes, this is due to enable_module() can accept "y" and "m".
> How about forcing enable_module() to accept "m" ?

I think we could change 

       - CONFIG_BLK_DEV_PMEM
to
       - CONFIG_BLK_DEV_PMEM=m

The former will correspond to kernel's

       #define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option))

while the latter correspond to

       #define IS_MODULE(option) config_enabled(option##_MODULE)

And add logic to handle the =m case. Currently we only have
enable_module() which corresponds to kernel's IS_ENABLED().

> 23 # CONFIG_XXX=m => unchange
> 24 # CONFIG_XXX=y => unchange
> 25 # CONFIG_XXX is not set => CONFIG_XXX=m
> 26 enable_module()

The behavior here is good for its current callers, except the "module"
in the function name might be a bit misleading.

Thanks,
Fengguang