aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/kbuild/makefiles.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/kbuild/makefiles.txt')
-rw-r--r--Documentation/kbuild/makefiles.txt37
1 files changed, 19 insertions, 18 deletions
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 71c602d61680..f29dca374aa2 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -187,34 +187,35 @@ more details, with real examples.
187 Note: In this example $(CONFIG_ISDN_PPP_BSDCOMP) evaluates to 'm' 187 Note: In this example $(CONFIG_ISDN_PPP_BSDCOMP) evaluates to 'm'
188 188
189 If a kernel module is built from several source files, you specify 189 If a kernel module is built from several source files, you specify
190 that you want to build a module in the same way as above. 190 that you want to build a module in the same way as above; however,
191 191 kbuild needs to know which object files you want to build your
192 Kbuild needs to know which the parts that you want to build your 192 module from, so you have to tell it by setting a $(<module_name>-y)
193 module from, so you have to tell it by setting an 193 variable.
194 $(<module_name>-objs) variable.
195 194
196 Example: 195 Example:
197 #drivers/isdn/i4l/Makefile 196 #drivers/isdn/i4l/Makefile
198 obj-$(CONFIG_ISDN) += isdn.o 197 obj-$(CONFIG_ISDN_I4L) += isdn.o
199 isdn-objs := isdn_net_lib.o isdn_v110.o isdn_common.o 198 isdn-y := isdn_net_lib.o isdn_v110.o isdn_common.o
200 199
201 In this example, the module name will be isdn.o. Kbuild will 200 In this example, the module name will be isdn.o. Kbuild will
202 compile the objects listed in $(isdn-objs) and then run 201 compile the objects listed in $(isdn-y) and then run
203 "$(LD) -r" on the list of these files to generate isdn.o. 202 "$(LD) -r" on the list of these files to generate isdn.o.
204 203
205 Kbuild recognises objects used for composite objects by the suffix 204 Due to kbuild recognizing $(<module_name>-y) for composite objects,
206 -objs, and the suffix -y. This allows the Makefiles to use 205 you can use the value of a CONFIG_ symbol to optionally include an
207 the value of a CONFIG_ symbol to determine if an object is part 206 object file as part of a composite object.
208 of a composite object.
209 207
210 Example: 208 Example:
211 #fs/ext2/Makefile 209 #fs/ext2/Makefile
212 obj-$(CONFIG_EXT2_FS) += ext2.o 210 obj-$(CONFIG_EXT2_FS) += ext2.o
213 ext2-y := balloc.o bitmap.o 211 ext2-y := balloc.o dir.o file.o ialloc.o inode.o ioctl.o \
214 ext2-$(CONFIG_EXT2_FS_XATTR) += xattr.o 212 namei.o super.o symlink.o
215 213 ext2-$(CONFIG_EXT2_FS_XATTR) += xattr.o xattr_user.o \
216 In this example, xattr.o is only part of the composite object 214 xattr_trusted.o
217 ext2.o if $(CONFIG_EXT2_FS_XATTR) evaluates to 'y'. 215
216 In this example, xattr.o, xattr_user.o and xattr_trusted.o are only
217 part of the composite object ext2.o if $(CONFIG_EXT2_FS_XATTR)
218 evaluates to 'y'.
218 219
219 Note: Of course, when you are building objects into the kernel, 220 Note: Of course, when you are building objects into the kernel,
220 the syntax above will also work. So, if you have CONFIG_EXT2_FS=y, 221 the syntax above will also work. So, if you have CONFIG_EXT2_FS=y,