diff options
| author | Stephen Warren <swarren@nvidia.com> | 2013-02-05 12:06:28 -0700 |
|---|---|---|
| committer | Grant Likely <grant.likely@secretlab.ca> | 2013-02-08 14:38:07 +0000 |
| commit | 22435f38337ef6a8abb33574604e77c335b75d14 (patch) | |
| tree | 74b2748ef47b5f126113911d7585f5b47ab80b2b /Documentation/kbuild | |
| parent | 1d0b1c74ed22d2614ae9206febf956f0b22c81a5 (diff) | |
kbuild: create a rule to run the pre-processor on *.dts files
Create cmd_dtc_cpp to run the C pre-processor on *.dts file before
passing them to dtc for final compilation. This allows the use of #define
and #include within the .dts file.
Acked-by: Simon Glass <sjg@chromium.org>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Michal Marek <mmarek@suse.cz>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Diffstat (limited to 'Documentation/kbuild')
| -rw-r--r-- | Documentation/kbuild/makefiles.txt | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index 14c3f4f1b617..5198b742fde1 100644 --- a/Documentation/kbuild/makefiles.txt +++ b/Documentation/kbuild/makefiles.txt @@ -1186,6 +1186,29 @@ When kbuild executes, the following steps are followed (roughly): clean-files += *.dtb DTC_FLAGS ?= -p 1024 + dtc_cpp + This is just like dtc as describe above, except that the C pre- + processor is invoked upon the .dtsp file before compiling the result + with dtc. + + In order for build dependencies to work, all files compiled using + dtc_cpp must use the C pre-processor's #include functionality and not + dtc's /include/ functionality. + + Using the C pre-processor allows use of #define to create named + constants. In turn, the #defines will typically appear in a header + file, which may be shared with regular C code. Since the dtc language + represents a data structure rather than code in C syntax, similar + restrictions are placed on a header file included by a device tree + file as for a header file included by an assembly language file. + In particular, the C pre-processor is passed -x assembler-with-cpp, + which sets macro __ASSEMBLY__. __DTS__ is also set. These allow header + files to restrict their content to that compatible with device tree + source. + + A central rule exists to create $(obj)/%.dtb from $(src)/%.dtsp; + architecture Makefiles do no need to explicitly write out that rule. + --- 6.8 Custom kbuild commands When kbuild is executing with KBUILD_VERBOSE=0, then only a shorthand |