diff options
Diffstat (limited to 'Documentation/kbuild')
| -rw-r--r-- | Documentation/kbuild/kconfig-language.rst | 5 | ||||
| -rw-r--r-- | Documentation/kbuild/makefiles.rst | 33 | ||||
| -rw-r--r-- | Documentation/kbuild/modules.rst | 13 |
3 files changed, 19 insertions, 32 deletions
diff --git a/Documentation/kbuild/kconfig-language.rst b/Documentation/kbuild/kconfig-language.rst index 74bef19f69f0..231e6a64957f 100644 --- a/Documentation/kbuild/kconfig-language.rst +++ b/Documentation/kbuild/kconfig-language.rst @@ -196,14 +196,11 @@ applicable everywhere (see syntax). or equal to the first symbol and smaller than or equal to the second symbol. -- help text: "help" or "---help---" +- help text: "help" This defines a help text. The end of the help text is determined by the indentation level, this means it ends at the first line which has a smaller indentation than the first line of the help text. - "---help---" and "help" do not differ in behaviour, "---help---" is - used to help visually separate configuration logic from help within - the file as an aid to developers. - misc options: "option" <symbol>[=<value>] diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst index b89c88168d6a..d7e6534a8505 100644 --- a/Documentation/kbuild/makefiles.rst +++ b/Documentation/kbuild/makefiles.rst @@ -297,9 +297,19 @@ more details, with real examples. If CONFIG_EXT2_FS is set to either 'y' (built-in) or 'm' (modular) the corresponding obj- variable will be set, and kbuild will descend down in the ext2 directory. - Kbuild only uses this information to decide that it needs to visit - the directory, it is the Makefile in the subdirectory that - specifies what is modular and what is built-in. + + Kbuild uses this information not only to decide that it needs to visit + the directory, but also to decide whether or not to link objects from + the directory into vmlinux. + + When Kbuild descends into the directory with 'y', all built-in objects + from that directory are combined into the built-in.a, which will be + eventually linked into vmlinux. + + When Kbuild descends into the directory with 'm', in contrast, nothing + from that directory will be linked into vmlinux. If the Makefile in + that directory specifies obj-y, those objects will be left orphan. + It is very likely a bug of the Makefile or of dependencies in Kconfig. It is good practice to use a `CONFIG_` variable when assigning directory names. This allows kbuild to totally skip the directory if the @@ -1115,23 +1125,6 @@ When kbuild executes, the following steps are followed (roughly): 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.a. - header-test-y - - header-test-y specifies headers (`*.h`) in the current directory that - should be compile tested to ensure they are self-contained, - i.e. compilable as standalone units. If CONFIG_HEADER_TEST is enabled, - this builds them as part of extra-y. - - header-test-pattern-y - - This works as a weaker version of header-test-y, and accepts wildcard - patterns. The typical usage is:: - - header-test-pattern-y += *.h - - This specifies all the files that matches to `*.h` in the current - directory, but the files in 'header-test-' are excluded. - 6.7 Commands useful for building a boot image --------------------------------------------- diff --git a/Documentation/kbuild/modules.rst b/Documentation/kbuild/modules.rst index 774a998dcf37..69fa48ee93d6 100644 --- a/Documentation/kbuild/modules.rst +++ b/Documentation/kbuild/modules.rst @@ -492,11 +492,8 @@ build. to the symbols from the kernel to check if all external symbols are defined. This is done in the MODPOST step. modpost obtains the symbols by reading Module.symvers from the kernel source - tree. If a Module.symvers file is present in the directory - where the external module is being built, this file will be - read too. During the MODPOST step, a new Module.symvers file - will be written containing all exported symbols that were not - defined in the kernel. + tree. During the MODPOST step, a new Module.symvers file will be + written containing all exported symbols from that external module. 6.3 Symbols From Another External Module ---------------------------------------- @@ -504,7 +501,7 @@ build. Sometimes, an external module uses exported symbols from another external module. Kbuild needs to have full knowledge of all symbols to avoid spitting out warnings about undefined - symbols. Three solutions exist for this situation. + symbols. Two solutions exist for this situation. NOTE: The method with a top-level kbuild file is recommended but may be impractical in certain situations. @@ -544,8 +541,8 @@ build. all symbols defined and not part of the kernel. Use "make" variable KBUILD_EXTRA_SYMBOLS - If it is impractical to copy Module.symvers from - another module, you can assign a space separated list + If it is impractical to add a top-level kbuild file, + you can assign a space separated list of files to KBUILD_EXTRA_SYMBOLS in your build file. These files will be loaded by modpost during the initialization of its symbol tables. |