Merge branch 'kbuild/rc-fixes' into kbuild/kconfig
We need to revert the temporary hack in 71ebc01, hence the merge.
This commit is contained in:
Michal Marek
@@ -22,11 +22,33 @@ building C files and assembler files.
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KAFLAGS
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--------------------------------------------------
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Additional options to the assembler.
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Additional options to the assembler (for built-in and modules).
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AFLAGS_MODULE
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--------------------------------------------------
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Addtional module specific options to use for $(AS).
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AFLAGS_KERNEL
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--------------------------------------------------
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Addtional options for $(AS) when used for assembler
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code for code that is compiled as built-in.
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KCFLAGS
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--------------------------------------------------
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Additional options to the C compiler.
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Additional options to the C compiler (for built-in and modules).
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CFLAGS_KERNEL
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--------------------------------------------------
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Addtional options for $(CC) when used to compile
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code that is compiled as built-in.
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CFLAGS_MODULE
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--------------------------------------------------
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Addtional module specific options to use for $(CC).
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LDFLAGS_MODULE
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--------------------------------------------------
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Additional options used for $(LD) when linking modules.
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KBUILD_VERBOSE
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--------------------------------------------------
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@@ -40,15 +62,15 @@ Set the directory to look for the kernel source when building external
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modules.
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The directory can be specified in several ways:
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1) Use "M=..." on the command line
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2) Environmnet variable KBUILD_EXTMOD
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3) Environmnet variable SUBDIRS
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2) Environment variable KBUILD_EXTMOD
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3) Environment variable SUBDIRS
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The possibilities are listed in the order they take precedence.
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Using "M=..." will always override the others.
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KBUILD_OUTPUT
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--------------------------------------------------
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Specify the output directory when building the kernel.
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The output directory can also be specificed using "O=...".
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The output directory can also be specified using "O=...".
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Setting "O=..." takes precedence over KBUILD_OUTPUT.
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ARCH
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@@ -90,7 +112,7 @@ The script will be called with the following arguments:
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$3 - kernel map file
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$4 - default install path (use root directory if blank)
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The implmentation of "make install" is architecture specific
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The implementation of "make install" is architecture specific
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and it may differ from the above.
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INSTALLKERNEL is provided to enable the possibility to
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@@ -45,7 +45,6 @@ This document describes the Linux kernel Makefiles.
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--- 7.1 header-y
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--- 7.2 objhdr-y
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--- 7.3 destination-y
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--- 7.4 unifdef-y (deprecated)
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=== 8 Kbuild Variables
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=== 9 Makefile language
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@@ -168,7 +167,7 @@ more details, with real examples.
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#drivers/isdn/i4l/Makefile
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# Makefile for the kernel ISDN subsystem and device drivers.
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# Each configuration option enables a list of files.
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obj-$(CONFIG_ISDN) += isdn.o
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obj-$(CONFIG_ISDN_I4L) += isdn.o
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obj-$(CONFIG_ISDN_PPP_BSDCOMP) += isdn_bsdcomp.o
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--- 3.3 Loadable module goals - obj-m
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@@ -187,34 +186,35 @@ more details, with real examples.
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Note: In this example $(CONFIG_ISDN_PPP_BSDCOMP) evaluates to 'm'
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If a kernel module is built from several source files, you specify
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that you want to build a module in the same way as above.
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Kbuild needs to know which the parts that you want to build your
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module from, so you have to tell it by setting an
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$(<module_name>-objs) variable.
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that you want to build a module in the same way as above; however,
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kbuild needs to know which object files you want to build your
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module from, so you have to tell it by setting a $(<module_name>-y)
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variable.
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Example:
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#drivers/isdn/i4l/Makefile
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obj-$(CONFIG_ISDN) += isdn.o
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isdn-objs := isdn_net_lib.o isdn_v110.o isdn_common.o
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obj-$(CONFIG_ISDN_I4L) += isdn.o
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isdn-y := isdn_net_lib.o isdn_v110.o isdn_common.o
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In this example, the module name will be isdn.o. Kbuild will
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compile the objects listed in $(isdn-objs) and then run
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compile the objects listed in $(isdn-y) and then run
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"$(LD) -r" on the list of these files to generate isdn.o.
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Kbuild recognises objects used for composite objects by the suffix
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-objs, and the suffix -y. This allows the Makefiles to use
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the value of a CONFIG_ symbol to determine if an object is part
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of a composite object.
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Due to kbuild recognizing $(<module_name>-y) for composite objects,
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you can use the value of a CONFIG_ symbol to optionally include an
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object file as part of a composite object.
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Example:
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#fs/ext2/Makefile
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obj-$(CONFIG_EXT2_FS) += ext2.o
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ext2-y := balloc.o bitmap.o
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ext2-$(CONFIG_EXT2_FS_XATTR) += xattr.o
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obj-$(CONFIG_EXT2_FS) += ext2.o
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ext2-y := balloc.o dir.o file.o ialloc.o inode.o ioctl.o \
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namei.o super.o symlink.o
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ext2-$(CONFIG_EXT2_FS_XATTR) += xattr.o xattr_user.o \
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xattr_trusted.o
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In this example, xattr.o is only part of the composite object
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ext2.o if $(CONFIG_EXT2_FS_XATTR) evaluates to 'y'.
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In this example, xattr.o, xattr_user.o and xattr_trusted.o are only
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part of the composite object ext2.o if $(CONFIG_EXT2_FS_XATTR)
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evaluates to 'y'.
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Note: Of course, when you are building objects into the kernel,
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the syntax above will also work. So, if you have CONFIG_EXT2_FS=y,
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@@ -244,12 +244,12 @@ more details, with real examples.
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may contain both a built-in.o and a lib.a file.
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Example:
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#arch/i386/lib/Makefile
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lib-y := checksum.o delay.o
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#arch/x86/lib/Makefile
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lib-y := delay.o
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This will create a library lib.a based on checksum.o and delay.o.
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For kbuild to actually recognize that there is a lib.a being built,
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the directory shall be listed in libs-y.
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This will create a library lib.a based on delay.o. For kbuild to
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actually recognize that there is a lib.a being built, the directory
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shall be listed in libs-y.
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See also "6.3 List directories to visit when descending".
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Use of lib-y is normally restricted to lib/ and arch/*/lib.
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@@ -284,43 +284,40 @@ more details, with real examples.
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--- 3.7 Compilation flags
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ccflags-y, asflags-y and ldflags-y
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The three flags listed above applies only to the kbuild makefile
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where they are assigned. They are used for all the normal
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cc, as and ld invocation happenign during a recursive build.
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These three flags apply only to the kbuild makefile in which they
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are assigned. They are used for all the normal cc, as and ld
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invocations happening during a recursive build.
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Note: Flags with the same behaviour were previously named:
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EXTRA_CFLAGS, EXTRA_AFLAGS and EXTRA_LDFLAGS.
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They are yet supported but their use are deprecated.
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They are still supported but their usage is deprecated.
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ccflags-y specifies options for compiling C files with $(CC).
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ccflags-y specifies options for compiling with $(CC).
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Example:
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# drivers/sound/emu10k1/Makefile
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ccflags-y += -I$(obj)
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ccflags-$(DEBUG) += -DEMU10K1_DEBUG
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# drivers/acpi/Makefile
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ccflags-y := -Os
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ccflags-$(CONFIG_ACPI_DEBUG) += -DACPI_DEBUG_OUTPUT
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This variable is necessary because the top Makefile owns the
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variable $(KBUILD_CFLAGS) and uses it for compilation flags for the
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entire tree.
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asflags-y is a similar string for per-directory options
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when compiling assembly language source.
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asflags-y specifies options for assembling with $(AS).
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Example:
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#arch/x86_64/kernel/Makefile
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asflags-y := -traditional
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#arch/sparc/kernel/Makefile
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asflags-y := -ansi
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ldflags-y is a string for per-directory options to $(LD).
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ldflags-y specifies options for linking with $(LD).
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Example:
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#arch/m68k/fpsp040/Makefile
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ldflags-y := -x
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#arch/cris/boot/compressed/Makefile
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ldflags-y += -T $(srctree)/$(src)/decompress_$(arch-y).lds
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subdir-ccflags-y, subdir-asflags-y
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The two flags listed above are similar to ccflags-y and as-falgs-y.
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The difference is that the subdir- variants has effect for the kbuild
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file where tey are present and all subdirectories.
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The two flags listed above are similar to ccflags-y and asflags-y.
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The difference is that the subdir- variants have effect for the kbuild
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file where they are present and all subdirectories.
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Options specified using subdir-* are added to the commandline before
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the options specified using the non-subdir variants.
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@@ -340,18 +337,18 @@ more details, with real examples.
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CFLAGS_aha152x.o = -DAHA152X_STAT -DAUTOCONF
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CFLAGS_gdth.o = # -DDEBUG_GDTH=2 -D__SERIAL__ -D__COM2__ \
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-DGDTH_STATISTICS
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CFLAGS_seagate.o = -DARBITRATE -DPARITY -DSEAGATE_USE_ASM
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These three lines specify compilation flags for aha152x.o,
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gdth.o, and seagate.o
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These two lines specify compilation flags for aha152x.o and gdth.o.
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$(AFLAGS_$@) is a similar feature for source files in assembly
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languages.
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Example:
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# arch/arm/kernel/Makefile
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AFLAGS_head-armv.o := -DTEXTADDR=$(TEXTADDR) -traditional
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AFLAGS_head-armo.o := -DTEXTADDR=$(TEXTADDR) -traditional
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AFLAGS_head.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
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AFLAGS_crunch-bits.o := -Wa,-mcpu=ep9312
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AFLAGS_iwmmxt.o := -Wa,-mcpu=iwmmxt
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--- 3.9 Dependency tracking
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@@ -923,16 +920,33 @@ When kbuild executes, the following steps are followed (roughly):
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The first example utilises the trick that a config option expands
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to 'y' when selected.
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CFLAGS_KERNEL $(CC) options specific for built-in
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KBUILD_AFLAGS_KERNEL $(AS) options specific for built-in
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$(CFLAGS_KERNEL) contains extra C compiler flags used to compile
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$(KBUILD_AFLAGS_KERNEL) contains extra C compiler flags used to compile
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resident kernel code.
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CFLAGS_MODULE $(CC) options specific for modules
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KBUILD_AFLAGS_MODULE Options for $(AS) when building modules
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$(CFLAGS_MODULE) contains extra C compiler flags used to compile code
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for loadable kernel modules.
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$(KBUILD_AFLAGS_MODULE) is used to add arch specific options that
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are used for $(AS).
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From commandline AFLAGS_MODULE shall be used (see kbuild.txt).
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KBUILD_CFLAGS_KERNEL $(CC) options specific for built-in
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$(KBUILD_CFLAGS_KERNEL) contains extra C compiler flags used to compile
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resident kernel code.
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KBUILD_CFLAGS_MODULE Options for $(CC) when building modules
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$(KBUILD_CFLAGS_MODULE) is used to add arch specific options that
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are used for $(CC).
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From commandline CFLAGS_MODULE shall be used (see kbuild.txt).
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KBUILD_LDFLAGS_MODULE Options for $(LD) when linking modules
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$(KBUILD_LDFLAGS_MODULE) is used to add arch specific options
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used when linking modules. This is often a linker script.
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From commandline LDFLAGS_MODULE shall be used (see kbuild.txt).
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--- 6.2 Add prerequisites to archprepare:
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@@ -1176,14 +1190,14 @@ When kbuild executes, the following steps are followed (roughly):
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=== 7 Kbuild syntax for exported headers
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The kernel include a set of headers that is exported to userspace.
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Many headers can be exported as-is but other headers requires a
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Many headers can be exported as-is but other headers require a
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minimal pre-processing before they are ready for user-space.
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The pre-processing does:
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- drop kernel specific annotations
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- drop include of compiler.h
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- drop all sections that is kernel internat (guarded by ifdef __KERNEL__)
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- drop all sections that are kernel internal (guarded by ifdef __KERNEL__)
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Each relevant directory contain a file name "Kbuild" which specify the
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Each relevant directory contains a file name "Kbuild" which specifies the
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headers to be exported.
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See subsequent chapter for the syntax of the Kbuild file.
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@@ -1230,11 +1244,6 @@ See subsequent chapter for the syntax of the Kbuild file.
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will be located in the directory "include/linux" when exported.
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--- 7.4 unifdef-y (deprecated)
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unifdef-y is deprecated. A direct replacement is header-y.
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=== 8 Kbuild Variables
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The top Makefile exports the following variables:
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Reference in New Issue
Block a user