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SubjectRe: [PATCH] kbuild: add Makefile snippet to list compiled files
On Wed, Dec 07, 2011 at 07:25:37AM +0100, Christian Dietrich wrote:
> To list the compilation units compiled by the current configuration the
> scripts/Makefile.list can be executed. It supports:
>
> - printing of all compilation units
> - all directories considered for compilation units
> - test if a given file is compiled by the configuration
> - use a different auto.conf
>
> Signed-off-by: Christian Dietrich <christian.dietrich@informatik.uni-erlangen.de>
> ---
> Hi,
>
> the following patch is a result of our research work at VAMOS[1],
> where we try to examine the perconditions under which a file is
> compiled into the linux kernel.
>
> While working on this, we needed a way to get all compilation units,
> which are compiled with the current configuration. And since this
> might be useful for others, I think it would be great to have this
> possibility in the mainline kernel.

I agree it would be useful, I have just a couple of comments.

- The user interface should either be a target of the main makefile or
a script. The make -f call seems a bit clumsy to me.
- You should perhaps start with less features. E.g. overriding the
location of auto.conf is hardly needed, also the compiled= option adds
some code, while the goal could be achieved by simply grepping the full
output.
- The deficiency of the approach is that it misses directories that are
only visited by an explicit make call in another makefile. An example
is the arch/x86/boot directory on x86. This should be at least
documented.
- The output can contain duplicates, if a object file is listed twice in
a Makefile (e.g. arch/x86/kernel/apic/ipi.o with x86_64 defconfig)
- lib-y is not considered.
- In general, it would be good to do a comparison between the output of
your Makefile and find -name '*.o' after a build and either fix or
document the differences.


> +# Read auto.conf if it exists, otherwise ignore
> +ifeq ($(auto_conf),)
> +-include include/config/auto.conf
> +else
> +include $(auto_conf)
> +endif

auto.conf missing should be considered fatal.


> +# The filename Kbuild has precedence over Makefile
> +kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
> +include $(if $(wildcard $(kbuild-dir)/Kbuild), $(kbuild-dir)/Kbuild, $(kbuild-dir)/Makefile)
> +
> +# Figure out what we need to build from the various variables
> +# ==========================================================================
> +
> +__subdir-y := $(patsubst %/,%,$(filter %/, $(obj-y)))
> +subdir-y += $(__subdir-y)
> +__subdir-m := $(patsubst %/,%,$(filter %/, $(obj-m)))
> +subdir-m += $(__subdir-m)
> +__subdir-n := $(patsubst %/,%,$(filter %/, $(obj-n)))
> +subdir-n += $(__subdir-n)
> +__subdir- := $(patsubst %/,%,$(filter %/, $(obj-)))
> +subdir- += $(__subdir-)
> +
> +# Subdirectories we need to descend into
> +subdir-ym := $(sort $(subdir-y) $(subdir-m))
> +subdir-ymn := $(sort $(subdir-ym) $(subdir-n) $(subdir-))

You are assiging variables that are immediatelly reassigned by
Makefile.lib (if there is a special reason that I'm missing, please
explain in a comment).

Michal


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