Re: cc-version not available to change EXTRA_CFLAGS

Sam Ravnborg
2006-01-21T22:57:43Z

On Sat, Jan 21, 2006 at 07:08:05PM +0100, Olaf Hering wrote:
>
> I want to add a gcc version check for reiserfs, on akpms request.
> This one doesnt work with 2.6.16rc1, havent checked if it ever worked.

I did the following:
- Moved definitions from Makefile to scripts/Kbuild.include
- Moved include of Kbuild.include up before include of kbuild file
- Documented the 'new' as-option
- Added new macro: cc-ifversion
- Added documentation for cc-ifversion

Let me know if this works for you.

> ifeq ($(CONFIG_PPC32),y)
> -EXTRA_CFLAGS := -O1
> +EXTRA_CFLAGS := $(shell set -x ; if [ $(call cc-version) -lt 0402 ] ; then echo $(call cc-option,-O1); fi ;)

For -O1 I do not see the point in using $(call cc-option ...).
I assume all gcc version does support -O1 - or?

Sam

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 443230b..14f925a 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -981,6 +981,20 @@ When kbuild executes the following steps
$(CC) is useally the gcc compiler, but other alternatives are
available.

+ as-option
+ as-option is used to check if $(CC) when used to compile
+ assembler (*.S) files supports the given option. An optional
+ second option may be specified if first option are not supported.
+
+ Example:
+ #arch/sh/Makefile
+ cflags-y += $(call as-option,-Wa$(comma)-isa=$(isa-y),)
+
+ In the above example cflags-y will be assinged the the option
+ -Wa$(comma)-isa=$(isa-y) if it is supported by $(CC).
+ The second argument is optional, and if supplied will be used
+ if first argument is not supported.
+
cc-option
cc-option is used to check if $(CC) support a given option, and not
supported to use an optional second option.
@@ -1039,7 +1053,21 @@ When kbuild executes the following steps

In the above example -mregparm=3 is only used for gcc version greater
than or equal to gcc 3.0.
-
+
+ cc-ifversion
+ cc-ifversion test the version of $(CC) and equals last argument if
+ version expression is true.
+
+ Example:
+ #fs/reiserfs/Makefile
+ EXTRA_CFLAGS := $(call cc-ifversion, -lt, 0402, -O1)
+
+ In this example EXTRA_CFLAGS will be assigned the value -O1 if the
+ $(CC) version is less than 4.2.
+ cc-ifversion takes all the shell operators:
+ -eq, -ne, -lt, -le, -gt, and -ge
+ The third parameter may be a text as in this example, but it may also
+ be an expanded variable or a macro.

=== 7 Kbuild Variables

diff --git a/Makefile b/Makefile
index 31bbc6a..da3c528 100644
--- a/Makefile
+++ b/Makefile
@@ -259,38 +259,6 @@ endif

export quiet Q KBUILD_VERBOSE

-######
-# cc support functions to be used (only) in arch/$(ARCH)/Makefile
-# See documentation in Documentation/kbuild/makefiles.txt
-
-# as-option
-# Usage: cflags-y += $(call as-option, -Wa$(comma)-isa=foo,)
-
-as-option = $(shell if $(CC) $(CFLAGS) $(1) -Wa,-Z -c -o /dev/null \
- -xassembler /dev/null > /dev/null 2>&1; then echo "$(1)"; \
- else echo "$(2)"; fi ;)
-
-# cc-option
-# Usage: cflags-y += $(call cc-option, -march=winchip-c6, -march=i586)
-
-cc-option = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
- > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;)
-
-# cc-option-yn
-# Usage: flag := $(call cc-option-yn, -march=winchip-c6)
-cc-option-yn = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
- > /dev/null 2>&1; then echo "y"; else echo "n"; fi;)
-
-# cc-option-align
-# Prefix align with either -falign or -malign
-cc-option-align = $(subst -functions=0,,\
- $(call cc-option,-falign-functions=0,-malign-functions=0))
-
-# cc-version
-# Usage gcc-ver := $(call cc-version $(CC))
-cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh \
- $(if $(1), $(1), $(CC)))
-

# Look for make include files relative to root of kernel src
MAKEFLAGS += --include-dir=$(srctree)
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 0168d6c..92ce94b 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -44,6 +44,43 @@ define filechk
fi
endef

+######
+# cc support functions to be used (only) in arch/$(ARCH)/Makefile
+# See documentation in Documentation/kbuild/makefiles.txt
+
+# as-option
+# Usage: cflags-y += $(call as-option, -Wa$(comma)-isa=foo,)
+
+as-option = $(shell if $(CC) $(CFLAGS) $(1) -Wa,-Z -c -o /dev/null \
+ -xassembler /dev/null > /dev/null 2>&1; then echo "$(1)"; \
+ else echo "$(2)"; fi ;)
+
+# cc-option
+# Usage: cflags-y += $(call cc-option, -march=winchip-c6, -march=i586)
+
+cc-option = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
+ > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;)
+
+# cc-option-yn
+# Usage: flag := $(call cc-option-yn, -march=winchip-c6)
+cc-option-yn = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
+ > /dev/null 2>&1; then echo "y"; else echo "n"; fi;)
+
+# cc-option-align
+# Prefix align with either -falign or -malign
+cc-option-align = $(subst -functions=0,,\
+ $(call cc-option,-falign-functions=0,-malign-functions=0))
+
+# cc-version
+# Usage gcc-ver := $(call cc-version, $(CC))
+cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh \
+ $(if $(1), $(1), $(CC)))
+
+# cc-ifversion
+# Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
+cc-ifversion = $(shell if [ $(call cc-version, $(CC)) $(1) $(2) ]; then \
+ echo $(3); fi;)
+
###
# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
# Usage:
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index c33e62b..2737765 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -10,11 +10,12 @@ __build:
# Read .config if it exist, otherwise ignore
-include .config

+include scripts/Kbuild.include
+
# 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)

-include scripts/Kbuild.include
include scripts/Makefile.lib

ifdef host-progs