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kbuild: fix for some typos in Documentation/makefiles.txt

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I noticed a few typos while reading makefiles.txt to learn about the
kbuild system.  Attached is a patch against 2.6.18 to fix them.
Remove trailing whitespace while we are there..

Signed-off-by:  Bryce Harrington <bryce@osdl.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
This commit is contained in:
Bryce Harrington 2006-09-20 12:43:37 -07:00 committed by Sam Ravnborg
parent 1c7bafe720
commit 39e6e9cf90
1 changed files with 43 additions and 40 deletions
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83
Documentation/kbuild/makefiles.txt
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@ -22,7 +22,7 @@ This document describes the Linux kernel Makefiles.
=== 4 Host Program support === 4 Host Program support
--- 4.1 Simple Host Program --- 4.1 Simple Host Program
--- 4.2 Composite Host Programs --- 4.2 Composite Host Programs
--- 4.3 Defining shared libraries --- 4.3 Defining shared libraries
--- 4.4 Using C++ for host programs --- 4.4 Using C++ for host programs
--- 4.5 Controlling compiler options for host programs --- 4.5 Controlling compiler options for host programs
--- 4.6 When host programs are actually built --- 4.6 When host programs are actually built
@ -69,7 +69,7 @@ architecture-specific information to the top Makefile.
Each subdirectory has a kbuild Makefile which carries out the commands Each subdirectory has a kbuild Makefile which carries out the commands
passed down from above. The kbuild Makefile uses information from the passed down from above. The kbuild Makefile uses information from the
.config file to construct various file lists used by kbuild to build .config file to construct various file lists used by kbuild to build
any built-in or modular targets. any built-in or modular targets.
scripts/Makefile.* contains all the definitions/rules etc. that scripts/Makefile.* contains all the definitions/rules etc. that
@ -203,9 +203,9 @@ more details, with real examples.
Example: Example:
#fs/ext2/Makefile #fs/ext2/Makefile
obj-$(CONFIG_EXT2_FS) += ext2.o obj-$(CONFIG_EXT2_FS) += ext2.o
ext2-y := balloc.o bitmap.o ext2-y := balloc.o bitmap.o
ext2-$(CONFIG_EXT2_FS_XATTR) += xattr.o ext2-$(CONFIG_EXT2_FS_XATTR) += xattr.o
In this example, xattr.o is only part of the composite object In this example, xattr.o is only part of the composite object
ext2.o if $(CONFIG_EXT2_FS_XATTR) evaluates to 'y'. ext2.o if $(CONFIG_EXT2_FS_XATTR) evaluates to 'y'.
@ -244,7 +244,7 @@ more details, with real examples.
For kbuild to actually recognize that there is a lib.a being built, For kbuild to actually recognize that there is a lib.a being built,
the directory shall be listed in libs-y. the directory shall be listed in libs-y.
See also "6.3 List directories to visit when descending". See also "6.3 List directories to visit when descending".
Use of lib-y is normally restricted to lib/ and arch/*/lib. Use of lib-y is normally restricted to lib/ and arch/*/lib.
--- 3.6 Descending down in directories --- 3.6 Descending down in directories
@ -408,7 +408,7 @@ more details, with real examples.
if first argument is not supported. if first argument is not supported.
ld-option ld-option
ld-option is used to check if $(CC) when used to link object files ld-option is used to check if $(CC) when used to link object files
supports the given option. An optional second option may be supports the given option. An optional second option may be
specified if first option are not supported. specified if first option are not supported.
@ -435,7 +435,7 @@ more details, with real examples.
cflags-y will be assigned no value if first option is not supported. cflags-y will be assigned no value if first option is not supported.
cc-option-yn cc-option-yn
cc-option-yn is used to check if gcc supports a given option cc-option-yn is used to check if gcc supports a given option
and return 'y' if supported, otherwise 'n'. and return 'y' if supported, otherwise 'n'.
Example: Example:
@ -443,7 +443,7 @@ more details, with real examples.
biarch := $(call cc-option-yn, -m32) biarch := $(call cc-option-yn, -m32)
aflags-$(biarch) += -a32 aflags-$(biarch) += -a32
cflags-$(biarch) += -m32 cflags-$(biarch) += -m32
In the above example, $(biarch) is set to y if $(CC) supports the -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) option. When $(biarch) equals 'y', the expanded variables $(aflags-y)
and $(cflags-y) will be assigned the values -a32 and -m32, and $(cflags-y) will be assigned the values -a32 and -m32,
@ -457,13 +457,13 @@ more details, with real examples.
cc-option-align = -malign cc-option-align = -malign
gcc >= 3.00 gcc >= 3.00
cc-option-align = -falign cc-option-align = -falign
Example: Example:
CFLAGS += $(cc-option-align)-functions=4 CFLAGS += $(cc-option-align)-functions=4
In the above example, the option -falign-functions=4 is used for In the above example, the option -falign-functions=4 is used for
gcc >= 3.00. For gcc < 3.00, -malign-functions=4 is used. gcc >= 3.00. For gcc < 3.00, -malign-functions=4 is used.
cc-version cc-version
cc-version returns a numerical version of the $(CC) compiler version. cc-version returns a numerical version of the $(CC) compiler version.
The format is <major><minor> where both are two digits. So for example The format is <major><minor> where both are two digits. So for example
@ -491,7 +491,7 @@ more details, with real examples.
In this example, EXTRA_CFLAGS will be assigned the value -O1 if the In this example, EXTRA_CFLAGS will be assigned the value -O1 if the
$(CC) version is less than 4.2. $(CC) version is less than 4.2.
cc-ifversion takes all the shell operators: cc-ifversion takes all the shell operators:
-eq, -ne, -lt, -le, -gt, and -ge -eq, -ne, -lt, -le, -gt, and -ge
The third parameter may be a text as in this example, but it may also The third parameter may be a text as in this example, but it may also
be an expanded variable or a macro. be an expanded variable or a macro.
@ -507,7 +507,7 @@ The first step is to tell kbuild that a host program exists. This is
done utilising the variable hostprogs-y. done utilising the variable hostprogs-y.
The second step is to add an explicit dependency to the executable. The second step is to add an explicit dependency to the executable.
This can be done in two ways. Either add the dependency in a rule, This can be done in two ways. Either add the dependency in a rule,
or utilise the variable $(always). or utilise the variable $(always).
Both possibilities are described in the following. Both possibilities are described in the following.
@ -524,7 +524,7 @@ Both possibilities are described in the following.
Kbuild assumes in the above example that bin2hex is made from a single Kbuild assumes in the above example that bin2hex is made from a single
c-source file named bin2hex.c located in the same directory as c-source file named bin2hex.c located in the same directory as
the Makefile. the Makefile.
--- 4.2 Composite Host Programs --- 4.2 Composite Host Programs
Host programs can be made up based on composite objects. Host programs can be made up based on composite objects.
@ -535,7 +535,7 @@ Both possibilities are described in the following.
Example: Example:
#scripts/lxdialog/Makefile #scripts/lxdialog/Makefile
hostprogs-y := lxdialog hostprogs-y := lxdialog
lxdialog-objs := checklist.o lxdialog.o lxdialog-objs := checklist.o lxdialog.o
Objects with extension .o are compiled from the corresponding .c Objects with extension .o are compiled from the corresponding .c
@ -544,8 +544,8 @@ Both possibilities are described in the following.
Finally, the two .o files are linked to the executable, lxdialog. Finally, the two .o files are linked to the executable, lxdialog.
Note: The syntax <executable>-y is not permitted for host-programs. Note: The syntax <executable>-y is not permitted for host-programs.
--- 4.3 Defining shared libraries --- 4.3 Defining shared libraries
Objects with extension .so are considered shared libraries, and Objects with extension .so are considered shared libraries, and
will be compiled as position independent objects. will be compiled as position independent objects.
Kbuild provides support for shared libraries, but the usage Kbuild provides support for shared libraries, but the usage
@ -558,7 +558,7 @@ Both possibilities are described in the following.
hostprogs-y := conf hostprogs-y := conf
conf-objs := conf.o libkconfig.so conf-objs := conf.o libkconfig.so
libkconfig-objs := expr.o type.o libkconfig-objs := expr.o type.o
Shared libraries always require a corresponding -objs line, and Shared libraries always require a corresponding -objs line, and
in the example above the shared library libkconfig is composed by in the example above the shared library libkconfig is composed by
the two objects expr.o and type.o. the two objects expr.o and type.o.
@ -579,7 +579,7 @@ Both possibilities are described in the following.
In the example above the executable is composed of the C++ file In the example above the executable is composed of the C++ file
qconf.cc - identified by $(qconf-cxxobjs). qconf.cc - identified by $(qconf-cxxobjs).
If qconf is composed by a mixture of .c and .cc files, then an If qconf is composed by a mixture of .c and .cc files, then an
additional line can be used to identify this. additional line can be used to identify this.
@ -588,7 +588,7 @@ Both possibilities are described in the following.
hostprogs-y := qconf hostprogs-y := qconf
qconf-cxxobjs := qconf.o qconf-cxxobjs := qconf.o
qconf-objs := check.o qconf-objs := check.o
--- 4.5 Controlling compiler options for host programs --- 4.5 Controlling compiler options for host programs
When compiling host programs, it is possible to set specific flags. When compiling host programs, it is possible to set specific flags.
@ -600,23 +600,23 @@ Both possibilities are described in the following.
Example: Example:
#scripts/lxdialog/Makefile #scripts/lxdialog/Makefile
HOST_EXTRACFLAGS += -I/usr/include/ncurses HOST_EXTRACFLAGS += -I/usr/include/ncurses
To set specific flags for a single file the following construction To set specific flags for a single file the following construction
is used: is used:
Example: Example:
#arch/ppc64/boot/Makefile #arch/ppc64/boot/Makefile
HOSTCFLAGS_piggyback.o := -DKERNELBASE=$(KERNELBASE) HOSTCFLAGS_piggyback.o := -DKERNELBASE=$(KERNELBASE)
It is also possible to specify additional options to the linker. It is also possible to specify additional options to the linker.
Example: Example:
#scripts/kconfig/Makefile #scripts/kconfig/Makefile
HOSTLOADLIBES_qconf := -L$(QTDIR)/lib HOSTLOADLIBES_qconf := -L$(QTDIR)/lib
When linking qconf, it will be passed the extra option When linking qconf, it will be passed the extra option
"-L$(QTDIR)/lib". "-L$(QTDIR)/lib".
--- 4.6 When host programs are actually built --- 4.6 When host programs are actually built
Kbuild will only build host-programs when they are referenced Kbuild will only build host-programs when they are referenced
@ -631,7 +631,7 @@ Both possibilities are described in the following.
$(obj)/devlist.h: $(src)/pci.ids $(obj)/gen-devlist $(obj)/devlist.h: $(src)/pci.ids $(obj)/gen-devlist
( cd $(obj); ./gen-devlist ) < $< ( cd $(obj); ./gen-devlist ) < $<
The target $(obj)/devlist.h will not be built before The target $(obj)/devlist.h will not be built before
$(obj)/gen-devlist is updated. Note that references to $(obj)/gen-devlist is updated. Note that references to
the host programs in special rules must be prefixed with $(obj). the host programs in special rules must be prefixed with $(obj).
@ -650,7 +650,7 @@ Both possibilities are described in the following.
--- 4.7 Using hostprogs-$(CONFIG_FOO) --- 4.7 Using hostprogs-$(CONFIG_FOO)
A typcal pattern in a Kbuild file looks like this: A typical pattern in a Kbuild file looks like this:
Example: Example:
#scripts/Makefile #scripts/Makefile
@ -682,7 +682,8 @@ When executing "make clean", the two files "devlist.h classlist.h" will
be deleted. Kbuild will assume files to be in same relative directory as the be deleted. Kbuild will assume files to be in same relative directory as the
Makefile except if an absolute path is specified (path starting with '/'). Makefile except if an absolute path is specified (path starting with '/').
To delete a directory hirachy use: To delete a directory hierarchy use:
Example: Example:
#scripts/package/Makefile #scripts/package/Makefile
clean-dirs := $(objtree)/debian/ clean-dirs := $(objtree)/debian/
@ -740,7 +741,7 @@ When kbuild executes, the following steps are followed (roughly):
5) Recursively descend down in all directories listed in 5) Recursively descend down in all directories listed in
init-* core* drivers-* net-* libs-* and build all targets. init-* core* drivers-* net-* libs-* and build all targets.
- The values of the above variables are expanded in arch/$(ARCH)/Makefile. - The values of the above variables are expanded in arch/$(ARCH)/Makefile.
6) All object files are then linked and the resulting file vmlinux is 6) All object files are then linked and the resulting file vmlinux is
located at the root of the obj tree. located at the root of the obj tree.
The very first objects linked are listed in head-y, assigned by The very first objects linked are listed in head-y, assigned by
arch/$(ARCH)/Makefile. arch/$(ARCH)/Makefile.
@ -762,7 +763,7 @@ When kbuild executes, the following steps are followed (roughly):
LDFLAGS := -m elf_s390 LDFLAGS := -m elf_s390
Note: EXTRA_LDFLAGS and LDFLAGS_$@ can be used to further customise Note: EXTRA_LDFLAGS and LDFLAGS_$@ can be used to further customise
the flags used. See chapter 7. the flags used. See chapter 7.
LDFLAGS_MODULE Options for $(LD) when linking modules LDFLAGS_MODULE Options for $(LD) when linking modules
LDFLAGS_MODULE is used to set specific flags for $(LD) when LDFLAGS_MODULE is used to set specific flags for $(LD) when
@ -845,7 +846,7 @@ When kbuild executes, the following steps are followed (roughly):
$(CFLAGS_MODULE) contains extra C compiler flags used to compile code $(CFLAGS_MODULE) contains extra C compiler flags used to compile code
for loadable kernel modules. for loadable kernel modules.
--- 6.2 Add prerequisites to archprepare: --- 6.2 Add prerequisites to archprepare:
The archprepare: rule is used to list prerequisites that need to be The archprepare: rule is used to list prerequisites that need to be
@ -869,7 +870,7 @@ When kbuild executes, the following steps are followed (roughly):
corresponding arch-specific section for modules; the module-building corresponding arch-specific section for modules; the module-building
machinery is all architecture-independent. machinery is all architecture-independent.
head-y, init-y, core-y, libs-y, drivers-y, net-y head-y, init-y, core-y, libs-y, drivers-y, net-y
$(head-y) lists objects to be linked first in vmlinux. $(head-y) lists objects to be linked first in vmlinux.
@ -926,7 +927,7 @@ When kbuild executes, the following steps are followed (roughly):
#arch/i386/Makefile #arch/i386/Makefile
define archhelp define archhelp
echo '* bzImage - Image (arch/$(ARCH)/boot/bzImage)' echo '* bzImage - Image (arch/$(ARCH)/boot/bzImage)'
endef endif
When make is executed without arguments, the first goal encountered When make is executed without arguments, the first goal encountered
will be built. In the top level Makefile the first goal present will be built. In the top level Makefile the first goal present
@ -938,7 +939,7 @@ When kbuild executes, the following steps are followed (roughly):
Example: Example:
#arch/i386/Makefile #arch/i386/Makefile
all: bzImage all: bzImage
When "make" is executed without arguments, bzImage will be built. When "make" is executed without arguments, bzImage will be built.
@ -961,7 +962,7 @@ When kbuild executes, the following steps are followed (roughly):
In this example, extra-y is used to list object files that In this example, extra-y is used to list object files that
shall be built, but shall not be linked as part of built-in.o. shall be built, but shall not be linked as part of built-in.o.
--- 6.6 Commands useful for building a boot image --- 6.6 Commands useful for building a boot image
Kbuild provides a few macros that are useful when building a Kbuild provides a few macros that are useful when building a
@ -995,7 +996,7 @@ When kbuild executes, the following steps are followed (roughly):
ld ld
Link target. Often, LDFLAGS_$@ is used to set specific options to ld. Link target. Often, LDFLAGS_$@ is used to set specific options to ld.
objcopy objcopy
Copy binary. Uses OBJCOPYFLAGS usually specified in Copy binary. Uses OBJCOPYFLAGS usually specified in
arch/$(ARCH)/Makefile. arch/$(ARCH)/Makefile.
@ -1053,7 +1054,7 @@ When kbuild executes, the following steps are followed (roughly):
BUILD arch/i386/boot/bzImage BUILD arch/i386/boot/bzImage
will be displayed with "make KBUILD_VERBOSE=0". will be displayed with "make KBUILD_VERBOSE=0".
--- 6.8 Preprocessing linker scripts --- 6.8 Preprocessing linker scripts
@ -1062,19 +1063,19 @@ When kbuild executes, the following steps are followed (roughly):
The script is a preprocessed variant of the file vmlinux.lds.S The script is a preprocessed variant of the file vmlinux.lds.S
located in the same directory. located in the same directory.
kbuild knows .lds files and includes a rule *lds.S -> *lds. kbuild knows .lds files and includes a rule *lds.S -> *lds.
Example: Example:
#arch/i386/kernel/Makefile #arch/i386/kernel/Makefile
always := vmlinux.lds always := vmlinux.lds
#Makefile #Makefile
export CPPFLAGS_vmlinux.lds += -P -C -U$(ARCH) export CPPFLAGS_vmlinux.lds += -P -C -U$(ARCH)
The assigment to $(always) is used to tell kbuild to build the The assignment to $(always) is used to tell kbuild to build the
target vmlinux.lds. target vmlinux.lds.
The assignment to $(CPPFLAGS_vmlinux.lds) tells kbuild to use the The assignment to $(CPPFLAGS_vmlinux.lds) tells kbuild to use the
specified options when building the target vmlinux.lds. specified options when building the target vmlinux.lds.
When building the *.lds target, kbuild uses the variables: When building the *.lds target, kbuild uses the variables:
CPPFLAGS : Set in top-level Makefile CPPFLAGS : Set in top-level Makefile
EXTRA_CPPFLAGS : May be set in the kbuild makefile EXTRA_CPPFLAGS : May be set in the kbuild makefile
@ -1180,3 +1181,5 @@ Language QA by Jan Engelhardt <jengelh@gmx.de>
- Generating offset header files. - Generating offset header files.
- Add more variables to section 7? - Add more variables to section 7?