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SubjectRe: [PATCH 2/6] kbuild: allow Kbuild to start from any directory
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Hi Yamada-san,

Thank you for the patches,

I like the direction this series is taking.

Small spelling error spotted below...
But as I've now gone through all of it I'll offer

Reviewed-by: Kieran Bingham <kbingham@kernel.org>


On 30/03/2019 12:04, Masahiro Yamada wrote:
> Kbuild always runs in the top of the output directory.
>
> If Make starts in the source directory with O=, it relocates the
> working directory to the location specified by O=.
>
> Also, users can start build from the output directory by using the
> Makefile generated by scripts/mkmakefile.
>
> With a little more effort, Kbuild will be able to start from any
> directory path.
>
> This commit allows to specify the source directory by using
> the -f option.
>
> For example, you can do:
>
> $ cd path/to/output/dir
> $ make -f path/to/source/dir/Makefile
>
> Or, for the equivalent behavior, you can do:
>
> $ make O=path/to/output/dir -f path/to/source/dir/Makefile
>
> KBUILD_SRC is now deprecated.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
>
> Makefile | 87 +++++++++++++++++++++++++++++++++++++---------------------------
> 1 file changed, 50 insertions(+), 37 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 9cbd367..1b2a70e 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -96,56 +96,65 @@ endif
>
> export quiet Q KBUILD_VERBOSE
>
> -# kbuild supports saving output files in a separate directory.
> -# To locate output files in a separate directory two syntaxes are supported.
> -# In both cases the working directory must be the root of the kernel src.
> +# Kbuild will save output files in the current working directory.
> +# This does not need to match to the root of the kernel source tree.
> +#
> +# For example, you can do this:
> +#
> +# cd /dir/to/store/output/files; make -f /dir/to/kernel/source/Makefile
> +#
> +# If you want to save output files in a different location, there are
> +# two syntaxes to specify it.
> +#
> # 1) O=
> # Use "make O=dir/to/store/output/files/"
> #
> # 2) Set KBUILD_OUTPUT
> -# Set the environment variable KBUILD_OUTPUT to point to the directory
> -# where the output files shall be placed.
> -# export KBUILD_OUTPUT=dir/to/store/output/files/
> -# make
> +# Set the environment variable KBUILD_OUTPUT to point to the output directory.
> +# export KBUILD_OUTPUT=dir/to/store/output/files/; make
> #
> # The O= assignment takes precedence over the KBUILD_OUTPUT environment
> # variable.
>
> -# KBUILD_SRC is not intended to be used by the regular user (for now),
> -# it is set on invocation of make with KBUILD_OUTPUT or O= specified.
> -
> -# OK, Make called in directory where kernel src resides
> -# Do we want to locate output files in a separate directory?
> +# Do we want to change the working directory?
> ifeq ("$(origin O)", "command line")
> KBUILD_OUTPUT := $(O)
> endif
>
> -ifneq ($(words $(subst :, ,$(CURDIR))), 1)
> - $(error main directory cannot contain spaces nor colons)
> +ifneq ($(KBUILD_OUTPUT),)
> +# Make's built-in functions such as $(abspath ...), $(realpath ...) cannot
> +# expand a shell special character '~'. We use a bit tredious way to handle it.

very minor, but I noticed while looking through the series ^^

s/bit tredious/somewhat tedious/



> +abs_objtree := $(shell mkdir -p $(KBUILD_OUTPUT) && cd $(KBUILD_OUTPUT) && pwd)
> +$(if $(abs_objtree),, \
> + $(error failed to create output directory "$(KBUILD_OUTPUT)"))
> +
> +# $(realpath ...) resolves symlinks
> +abs_objtree := $(realpath $(abs_objtree))
> +else
> +abs_objtree := $(CURDIR)
> +endif # ifneq ($(KBUILD_OUTPUT),)
> +
> +ifeq ($(abs_objtree),$(CURDIR))
> +# Suppress "Entering directory ..." unless we are changing the work directory.
> +MAKEFLAGS += --no-print-directory
> +else
> +need-sub-make := 1
> endif
>
> -ifneq ($(KBUILD_OUTPUT),)
> -# check that the output directory actually exists
> -saved-output := $(KBUILD_OUTPUT)
> -KBUILD_OUTPUT := $(shell mkdir -p $(KBUILD_OUTPUT) && cd $(KBUILD_OUTPUT) \
> - && pwd)
> -$(if $(KBUILD_OUTPUT),, \
> - $(error failed to create output directory "$(saved-output)"))
> +abs_srctree := $(realpath $(dir $(lastword $(MAKEFILE_LIST))))
> +
> +ifneq ($(words $(subst :, ,$(abs_srctree))), 1)
> +$(error source directory cannot contain spaces or colons)
> +endif
>
> +ifneq ($(abs_srctree),$(abs_objtree))
> # Look for make include files relative to root of kernel src
> #
> # This does not become effective immediately because MAKEFLAGS is re-parsed
> -# once after the Makefile is read. It is OK since we are going to invoke
> -# 'sub-make' below.
> -MAKEFLAGS += --include-dir=$(CURDIR)
> -
> +# once after the Makefile is read. We need to invoke sub-make.
> +MAKEFLAGS += --include-dir=$(abs_srctree)
> need-sub-make := 1
> -else
> -
> -# Do not print "Entering directory ..." at all for in-tree build.
> -MAKEFLAGS += --no-print-directory
> -
> -endif # ifneq ($(KBUILD_OUTPUT),)
> +endif
>
> ifneq ($(filter 3.%,$(MAKE_VERSION)),)
> # 'MAKEFLAGS += -rR' does not immediately become effective for GNU Make 3.x
> @@ -155,6 +164,7 @@ need-sub-make := 1
> $(lastword $(MAKEFILE_LIST)): ;
> endif
>
> +export abs_srctree abs_objtree
> export sub_make_done := 1
>
> ifeq ($(need-sub-make),1)
> @@ -166,9 +176,7 @@ $(filter-out _all sub-make $(lastword $(MAKEFILE_LIST)), $(MAKECMDGOALS)) _all:
>
> # Invoke a second make in the output directory, passing relevant variables
> sub-make:
> - $(Q)$(MAKE) \
> - $(if $(KBUILD_OUTPUT),-C $(KBUILD_OUTPUT) KBUILD_SRC=$(CURDIR)) \
> - -f $(CURDIR)/Makefile $(MAKECMDGOALS)
> + $(Q)$(MAKE) -C $(abs_objtree) -f $(abs_srctree)/Makefile $(MAKECMDGOALS)
>
> endif # need-sub-make
> endif # sub_make_done
> @@ -213,16 +221,21 @@ ifeq ("$(origin M)", "command line")
> KBUILD_EXTMOD := $(M)
> endif
>
> -ifeq ($(KBUILD_SRC),)
> +ifeq ($(abs_srctree),$(abs_objtree))
> # building in the source tree
> srctree := .
> else
> - ifeq ($(KBUILD_SRC)/,$(dir $(CURDIR)))
> + ifeq ($(abs_srctree)/,$(dir $(abs_objtree)))
> # building in a subdirectory of the source tree
> srctree := ..
> else
> - srctree := $(KBUILD_SRC)
> + srctree := $(abs_srctree)
> endif
> +
> + # TODO:
> + # KBUILD_SRC is only used to distinguish in-tree/out-of-tree build.
> + # Replace it with $(srctree) or something.
> + KBUILD_SRC := $(abs_srctree)
> endif
>
> export KBUILD_CHECKSRC KBUILD_EXTMOD KBUILD_SRC
>


--
--
Kieran

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