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b1992c3772
Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for
checked-in source files. It is merely a convention without any functional
difference. In fact, $(obj) and $(src) are exactly the same, as defined
in scripts/Makefile.build:
src := $(obj)
When the kernel is built in a separate output directory, $(src) does
not accurately reflect the source directory location. While Kbuild
resolves this discrepancy by specifying VPATH=$(srctree) to search for
source files, it does not cover all cases. For example, when adding a
header search path for local headers, -I$(srctree)/$(src) is typically
passed to the compiler.
This introduces inconsistency between upstream and downstream Makefiles
because $(src) is used instead of $(srctree)/$(src) for the latter.
To address this inconsistency, this commit changes the semantics of
$(src) so that it always points to the directory in the source tree.
Going forward, the variables used in Makefiles will have the following
meanings:
$(obj) - directory in the object tree
$(src) - directory in the source tree (changed by this commit)
$(objtree) - the top of the kernel object tree
$(srctree) - the top of the kernel source tree
Consequently, $(srctree)/$(src) in upstream Makefiles need to be replaced
with $(src).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
31 lines
929 B
Makefile
31 lines
929 B
Makefile
# SPDX-License-Identifier: GPL-2.0
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hostprogs-always-y += genksyms
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genksyms-objs := genksyms.o parse.tab.o lex.lex.o
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# FIXME: fix the ambiguous grammar in parse.y and delete this hack
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#
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# Suppress shift/reduce, reduce/reduce conflicts warnings
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# unless W=1 is specified.
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#
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# Just in case, run "$(YACC) --version" without suppressing stderr
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# so that 'bison: not found' will be displayed if it is missing.
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ifeq ($(findstring 1,$(KBUILD_EXTRA_WARN)),)
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quiet_cmd_bison_no_warn = $(quiet_cmd_bison)
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cmd_bison_no_warn = $(YACC) --version >/dev/null; \
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$(cmd_bison) 2>/dev/null
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$(obj)/pars%.tab.c $(obj)/pars%.tab.h: $(src)/pars%.y FORCE
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$(call if_changed,bison_no_warn)
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endif
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# -I needed for generated C source to include headers in source tree
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HOSTCFLAGS_parse.tab.o := -I $(src)
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HOSTCFLAGS_lex.lex.o := -I $(src)
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# dependencies on generated files need to be listed explicitly
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$(obj)/lex.lex.o: $(obj)/parse.tab.h
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