In Linux build system convention, pre-generated files are version- controlled with a "_shipped" suffix. During the kernel building, they are simply shipped (copied) removing the suffix. This approach can reduce external tool dependency for the kernel build, but it is tedious to manually regenerate such artifacts from developers' point of view. (We need to do "make REGENERATE_PARSERS=1" every time we touch real source files such as *.l, *.y) Some months ago, I sent out RFC patches to run flex, bison, and gperf during the build. In the review and test, Linus noticed gperf-3.1 had changed the lookup function prototype. Then, the use of gperf in kernel was entirely removed by commit bb3290d91695 ("Remove gperf usage from toolchain"). I tested several versions of flex and bison, and I was not hit by any compatibility issue except a flaw in flex-2.6.3; if you generate lexer for dtc and genksyms with flex-2.6.3, you will see "yywrap redefined" warning. This was not intentional, but a bug fixed by flex-2.6.4. Otherwise, flex and bison look fairly stable for a long time. This commit prepares some build rules to start removing the _shipped files. Also, document minimal requirement for flex and bison. Rationale for the minimal version: The -Wmissing-prototypes option of GCC reports "no previous prototype" warnings for lexers generated by flex-2.5.34, so I chose 2.5.35 as the required version for flex. Flex-2.5.35 was released in 2008. Bison looked more stable. I did not see any problem with bison-2.0, released in 2004. I did not test bison-1.x, but bison-2.0 should be old enough. Tested flex versions: 2.5.35 2.5.36 2.5.37 2.5.39 2.6.0 2.6.1 2.6.2 2.6.3 (*) 2.6.4 (*) flex-2.6.3 causes "yywrap redefined" warning Tested bison versions: 2.0 2.1 2.2 2.3 2.4 2.4.1 2.5.1 2.6 2.6.1 2.6.2 2.6.3 2.6.4 2.6.5 2.7 2.7.1 3.0 3.0.1 3.0.2 3.0.3 3.0.4 Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> --- Documentation/process/changes.rst | 25 +++++++++++++++++++++++++ scripts/Makefile.lib | 20 +++++++++++++++++--- 2 files changed, 42 insertions(+), 3 deletions(-) diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst index 560beae..fc9c7c3 100644 --- a/Documentation/process/changes.rst +++ b/Documentation/process/changes.rst @@ -32,6 +32,8 @@ you probably needn't concern yourself with isdn4k-utils. GNU C 3.2 gcc --version GNU make 3.81 make --version binutils 2.20 ld -v +flex 2.5.35 flex --version +bison 2.0 bison --version util-linux 2.10o fdformat --version module-init-tools 0.9.10 depmod -V e2fsprogs 1.41.4 e2fsck -V @@ -79,6 +81,19 @@ The build system has, as of 4.13, switched to using thin archives (`ar T`) rather than incremental linking (`ld -r`) for built-in.o intermediate steps. This requires binutils 2.20 or newer. +Flex +---- + +Since Linux 4.16, the build system generates lexical analisers +during build. This requires flex 2.5.35 or later. + + +Bison +----- + +Since Linux 4.16, the build system generates parsers +during build. This requires bison 2.0 or later. + Perl ---- @@ -333,6 +348,16 @@ Binutils - <https://www.kernel.org/pub/linux/devel/binutils/> +Flex +---- + +- <https://github.com/westes/flex/releases> + +Bison +----- + +- <ftp://ftp.gnu.org/gnu/bison/> + OpenSSL ------- diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index ee528e3..0f9ef3f 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -186,8 +186,6 @@ $(foreach m, $(notdir $1), \ $(addprefix $(obj)/, $(foreach s, $3, $($(m:%$(strip $2)=%$(s))))))) endef -ifdef REGENERATE_PARSERS - # LEX # --------------------------------------------------------------------------- LEX_PREFIX = $(if $(LEX_PREFIX_${baseprereq}),$(LEX_PREFIX_${baseprereq}),yy) @@ -195,9 +193,15 @@ LEX_PREFIX = $(if $(LEX_PREFIX_${baseprereq}),$(LEX_PREFIX_${baseprereq}),yy) quiet_cmd_flex = LEX $@ cmd_flex = $(LEX) -o$@ -L -P $(LEX_PREFIX) $< +ifdef REGENERATE_PARSERS .PRECIOUS: $(src)/%.lex.c_shipped $(src)/%.lex.c_shipped: $(src)/%.l $(call cmd,flex) +endif + +.PRECIOUS: $(obj)/%.lex.c +$(filter %.lex.c,$(targets)): $(obj)/%.lex.c: $(src)/%.l FORCE + $(call if_changed,flex) # YACC # --------------------------------------------------------------------------- @@ -206,19 +210,29 @@ YACC_PREFIX = $(if $(YACC_PREFIX_${baseprereq}),$(YACC_PREFIX_${baseprereq}),yy) quiet_cmd_bison = YACC $@ cmd_bison = $(YACC) -o$@ -t -l -p $(YACC_PREFIX) $< +ifdef REGENERATE_PARSERS .PRECIOUS: $(src)/%.tab.c_shipped $(src)/%.tab.c_shipped: $(src)/%.y $(call cmd,bison) +endif + +.PRECIOUS: $(obj)/%.tab.c +$(filter %.tab.c,$(targets)): $(obj)/%.tab.c: $(src)/%.y FORCE + $(call if_changed,bison) quiet_cmd_bison_h = YACC $@ cmd_bison_h = bison -o/dev/null --defines=$@ -t -l -p $(YACC_PREFIX) $< +ifdef REGENERATE_PARSERS .PRECIOUS: $(src)/%.tab.h_shipped $(src)/%.tab.h_shipped: $(src)/%.y $(call cmd,bison_h) - endif +.PRECIOUS: $(obj)/%.tab.h +$(filter %.tab.h,$(targets)): $(obj)/%.tab.h: $(src)/%.y FORCE + $(call if_changed,bison_h) + # Shipped files # =========================================================================== -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html