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Diffstat (limited to 'Documentation/kbuild/makefiles.rst')
| -rw-r--r-- | Documentation/kbuild/makefiles.rst | 45 |
1 files changed, 44 insertions, 1 deletions
diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst index 6515ebc12b6f..b81b8913a5a3 100644 --- a/Documentation/kbuild/makefiles.rst +++ b/Documentation/kbuild/makefiles.rst @@ -368,6 +368,14 @@ more details, with real examples. subdir-ccflags-y := -Werror + ccflags-remove-y, asflags-remove-y + These flags are used to remove particular flags for the compiler, + assembler invocations. + + Example:: + + ccflags-remove-$(CONFIG_MCOUNT) += -pg + CFLAGS_$@, AFLAGS_$@ CFLAGS_$@ and AFLAGS_$@ only apply to commands in current kbuild makefile. @@ -375,6 +383,9 @@ more details, with real examples. $(CFLAGS_$@) specifies per-file options for $(CC). The $@ part has a literal value which specifies the file that it is for. + CFLAGS_$@ has the higher priority than ccflags-remove-y; CFLAGS_$@ + can re-add compiler flags that were removed by ccflags-remove-y. + Example:: # drivers/scsi/Makefile @@ -387,6 +398,9 @@ more details, with real examples. $(AFLAGS_$@) is a similar feature for source files in assembly languages. + AFLAGS_$@ has the higher priority than asflags-remove-y; AFLAGS_$@ + can re-add assembler flags that were removed by asflags-remove-y. + Example:: # arch/arm/kernel/Makefile @@ -735,6 +749,10 @@ Both possibilities are described in the following. hostprogs := lxdialog always-y := $(hostprogs) + Kbuild provides the following shorthand for this: + + hostprogs-always-y := lxdialog + This will tell kbuild to build lxdialog even if not referenced in any rule. @@ -817,7 +835,32 @@ The syntax is quite similar. The difference is to use "userprogs" instead of 5.4 When userspace programs are actually built ---------------------------------------------- - Same as "When host programs are actually built". + Kbuild builds userspace programs only when told to do so. + There are two ways to do this. + + (1) Add it as the prerequisite of another file + + Example:: + + #net/bpfilter/Makefile + userprogs := bpfilter_umh + $(obj)/bpfilter_umh_blob.o: $(obj)/bpfilter_umh + + $(obj)/bpfilter_umh is built before $(obj)/bpfilter_umh_blob.o + + (2) Use always-y + + Example:: + + userprogs := binderfs_example + always-y := $(userprogs) + + Kbuild provides the following shorthand for this: + + userprogs-always-y := binderfs_example + + This will tell Kbuild to build binderfs_example when it visits this + Makefile. 6 Kbuild clean infrastructure ============================= |