Thanks Robert - a few comments..
Can you please address them and resubmit.
The changes that I did not comment are fine.
Thanks,
Sam
On Sat, Nov 17, 2007 at 12:38:57PM -0500, Robert P. J. Day wrote:
>
> Fix some typoes, and update some Makefile excerpts in the
> makefiles.txt file, so that the examples reflect actual existing code.
>
> Signed-off-by: Robert P. J. Day <[EMAIL PROTECTED]>
>
> ---
>
> the biggest set of patches was to just replace out-of-date Makefile
> snippets with existing snippets.
>
>
> diff --git a/Documentation/kbuild/makefiles.txt
> b/Documentation/kbuild/makefiles.txt
> index 7a77533..af6c798 100644
> --- a/Documentation/kbuild/makefiles.txt
> +++ b/Documentation/kbuild/makefiles.txt
> @@ -53,7 +53,7 @@ The Makefiles have five parts:
> .config the kernel configuration file.
> arch/$(ARCH)/Makefile the arch Makefile.
> scripts/Makefile.* common rules etc. for all kbuild Makefiles.
> - kbuild Makefiles there are about 500 of these.
> + kbuild Makefiles there are about 1000 of these.
>
> The top Makefile reads the .config file, which comes from the kernel
> configuration process.
> @@ -277,9 +277,9 @@ more details, with real examples.
> --- 3.7 Compilation flags
>
> ccflags-y, asflags-y and ldflags-y
> - The three flags listed above applies only to the kbuild makefile
> + The three flags listed above apply only to the kbuild makefile
> where they are assigned. They are used for all the normal
> - cc, as and ld invocation happenign during a recursive build.
> + cc, as and ld invocation happening during a recursive build.
> Note: Flags with the same behaviour were previously named:
> EXTRA_CFLAGS, EXTRA_AFLAGS and EXTRA_LDFLAGS.
> They are yet supported but their use are deprecated.
> @@ -287,9 +287,8 @@ more details, with real examples.
> ccflags-y specifies options for compiling C files with $(CC).
>
> Example:
> - # drivers/sound/emu10k1/Makefile
> - ccflags-y += -I$(obj)
> - ccflags-$(DEBUG) += -DEMU10K1_DEBUG
> + #arch/x86/boot/Makefile
> + $(obj)/bzImage: ccflags-y := -D__BIG_KERNEL__
It is more important to show the use of ccflags-$(CONFIG_xxx) than to
be an exact copy from the file.
In this case the correct fix is to update drivers/sound/emu10k1/Makefile
to use ccflags-y
>
>
> This variable is necessary because the top Makefile owns the
> @@ -300,15 +299,15 @@ more details, with real examples.
> when compiling assembly language source.
>
> Example:
> - #arch/x86_64/kernel/Makefile
> - asflags-y := -traditional
> + #arch/x86/boot/Makefile
> + $(obj)/zImage: asflags-y := $(SVGA_MODE) $(RAMDISK)
>
>
> ldflags-y is a string for per-directory options to $(LD).
>
> Example:
> - #arch/m68k/fpsp040/Makefile
> - ldflags-y := -x
> + #arch/h8300/Makefile
> + LDFLAGS += $(ldflags-y)
This file does not use ldflags-y from kbuild but a variable
of the same name.
Again the correct fix is to update the referenced file.
May I suggest you do that as a sweep over the full kernel?
For EXTRA_LDFLAGS the job is trivial...
>
> CFLAGS_$@, AFLAGS_$@
>
> @@ -398,9 +397,9 @@ more details, with real examples.
>
> Example:
> #arch/sh/Makefile
> - cflags-y += $(call as-option,-Wa$(comma)-isa=$(isa-y),)
> + isaflags-y := $(call as-option,-Wa$(comma)-isa=$(isa-y),)
>
> - In the above example, cflags-y will be assigned the option
> + In the above example, isaflags-y will be assigned the option
> -Wa$(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.
> @@ -411,10 +410,13 @@ more details, with real examples.
> specified if first option are not supported.
>
> Example:
> - #arch/i386/kernel/Makefile
> - vsyscall-flags += $(call ld-option,
> -Wl$(comma)--hash-style=sysv)
> + #arch/x86/vdso/Makefile
> + vdso-flags = -fPIC -shared -Wl,-soname=linux-vdso.so.1 \
> + $(call ld-option, -Wl$(comma)--hash-style=sysv) \
> + -Wl,-z,max-page-size=4096 -Wl,-z,common-page-size=4096
> +
>
> - In the above example, vsyscall-flags will be assigned the option
> + In the above example, vdso-flags will use the option
> -Wl$(comma)--hash-style=sysv if it is supported by $(CC).
> The second argument is optional, and if supplied will be used
> if first argument is not supported.
> @@ -423,20 +425,19 @@ more details, with real examples.
> as-instr checks if the assembler reports a specific instruction
> and then outputs either option1 or option2
> C escapes are supported in the test instruction
> - Note: as-instr-option uses KBUILD_AFLAGS for $(AS) options
This note is important - do not delete it. And it is correct - no?
>
> cc-option
> cc-option is used to check if $(CC) supports a given option, and not
> supported to use an optional second option.
>
> Example:
> - #arch/i386/Makefile
> - cflags-y += $(call cc-option,-march=pentium-mmx,-march=i586)
> + #arch/x86/Makefile_64
> + cflags-y += $(call cc-option,-funit-at-a-time)
Please update this to show usage with one and two arguments.
>
> - In the above example, cflags-y will be assigned the option
> - -march=pentium-mmx if supported by $(CC), otherwise -march=i586.
> - The second argument to cc-option is optional, and if omitted,
> - cflags-y will be assigned no value if first option is not supported.
> + In the above example, cflags-y will have appended to it the
> + option -funit-at-a-time if supported by $(CC). The second
> + argument to cc-option is optional and, if omitted, will be
> + represented by no value if the first option is not supported.
> Note: cc-option uses KBUILD_CFLAGS for $(CC) options
>
> cc-option-yn
> @@ -445,14 +446,16 @@ more details, with real examples.
>
> Example:
> #arch/ppc/Makefile
> - biarch := $(call cc-option-yn, -m32)
> - aflags-$(biarch) += -a32
> - cflags-$(biarch) += -m32
> -
> - In the above example, $(biarch) is set to y if $(CC) supports the -m32
> - option. When $(biarch) equals 'y', the expanded variables $(aflags-y)
> - and $(cflags-y) will be assigned the values -a32 and -m32,
> - respectively.
> + HAS_BIARCH := $(call cc-option-yn, -m32)
> + ifeq ($(HAS_BIARCH),y)
> + AS := $(AS) -a32
> + LD := $(LD) -m elf32ppc
> + CC := $(CC) -m32
> + endif
> +
> + In the above example, $(HAS_BIARCH) is set to y if $(CC) supports
> + the -m32 option, which subsequently affects the values of $(AS),
> + $(LD) and $(CC).
> Note: cc-option-yn uses KBUILD_CFLAGS for $(CC) options
>
> cc-option-align
> @@ -464,7 +467,13 @@ more details, with real examples.
> gcc >= 3.00
> cc-option-align = -falign
>
> - Example:
> + The correct value is set automatically in scripts/Kbuild.include:
> + # 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))
We should not include the implementation just to explain it.
Then it is better to make up an example.
> +
> + Example usage:
> KBUILD_CFLAGS += $(cc-option-align)-functions=4
>
> In the above example, the option -falign-functions=4 is used for
> @@ -475,18 +484,16 @@ more details, with real examples.
> cc-version returns a numerical version of the $(CC) compiler version.
> The format is <major><minor> where both are two digits. So for example
> gcc 3.41 would return 0341.
> - cc-version is useful when a specific $(CC) version is faulty in one
> - area, for example -mregparm=3 was broken in some gcc versions
> - even though the option was accepted by gcc.
>
> Example:
> - #arch/i386/Makefile
> - cflags-y += $(shell \
> - if [ $(call cc-version) -ge 0300 ] ; then \
> - echo "-mregparm=3"; fi ;)
> + #arch/ia64/Makefile
> + ifeq ($(call cc-version),0304)
> + cflags-$(CONFIG_ITANIUM) += -mtune=merced
> + cflags-$(CONFIG_MCKINLEY) += -mtune=mckinley
> + endif
>
> - In the above example, -mregparm=3 is only used for gcc version greater
> - than or equal to gcc 3.0.
> + In the above example, the "cflags" variable(s) will have some
> + specific options appended if gcc 3.4 is being used.
The variable is named cflags-y - not cflags.
>
> cc-ifversion
> cc-ifversion tests the version of $(CC) and equals last argument if
> @@ -494,10 +501,10 @@ more details, with real examples.
>
> Example:
> #fs/reiserfs/Makefile
> - ccflags-y := $(call cc-ifversion, -lt, 0402, -O1)
> + EXTRA_CFLAGS := $(call cc-ifversion, -lt, 0400, -O1)
EXTRA_CFLAGS is deprecated. Please update reiserfs/Makefile instead.
>
> - In this example, ccflags-y will be assigned the value -O1 if the
> - $(CC) version is less than 4.2.
> + In this example, EXTRA_CFLAGS will be assigned the value -O1 if the
> + $(CC) version is less than 4.0.
> 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
> @@ -509,12 +516,16 @@ more details, with real examples.
> cc-fullversion points out a more specific version than cc-version does.
>
> Example:
> - #arch/powerpc/Makefile
> - $(Q)if test "$(call cc-fullversion)" = "040200" ; then \
> + @if test "$(call cc-fullversion)" = "040200" \
> + && test "x${CONFIG_MODULES}${CONFIG_PPC64}" = "xyy" ; then \
> echo -n '*** GCC-4.2.0 cannot compile the 64-bit
> powerpc ' ; \
> + echo 'kernel with modules enabled.' ; \
> + echo -n '*** Please use a different GCC version or ' ; \
> + echo 'disable kernel modules' ; \
> false ; \
> fi
>
> +
> In this example for a specific GCC version the build will error out
> explaining
> to the user why it stops.
>
> @@ -533,11 +544,14 @@ more details, with real examples.
> is already set then leave it with the old value.
>
> Example:
> - #arch/m68k/Makefile
> + #arch/mips/Makefile
> ifneq ($(SUBARCH),$(ARCH))
> - ifeq ($(CROSS_COMPILE),)
> - CROSS_COMPILE := $(call cc-cross-prefix,
> m68k-linux-gnu-)
> - endif
> + ifeq ($(CROSS_COMPILE),)
> + CROSS_COMPILE := $(call cc-cross-prefix,
> + $(tool-archpref)-linux-
> + $(tool-archpref)-linux-gnu-
> + $(tool-archpref)-unknown-linux-gnu-)
> + endif
> endif
>
> === 4 Host Program support
> ========================================================================
> Robert P. J. Day
> Linux Consulting, Training and Annoying Kernel Pedantry
> Waterloo, Ontario, CANADA
>
> http://crashcourse.ca
> ========================================================================
> -
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