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Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/kbuild/makefiles.txt | 74 |
1 files changed, 31 insertions, 43 deletions
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index 9b9c4797fc55..e18daca65ccd 100644 --- a/Documentation/kbuild/makefiles.txt +++ b/Documentation/kbuild/makefiles.txt @@ -44,11 +44,11 @@ This document describes the Linux kernel Makefiles. --- 6.11 Post-link pass === 7 Kbuild syntax for exported headers - --- 7.1 header-y + --- 7.1 no-export-headers --- 7.2 genhdr-y - --- 7.3 destination-y - --- 7.4 generic-y - --- 7.5 generated-y + --- 7.3 generic-y + --- 7.4 generated-y + --- 7.5 mandatory-y === 8 Kbuild Variables === 9 Makefile language @@ -1236,7 +1236,7 @@ When kbuild executes, the following steps are followed (roughly): that may be shared between individual architectures. The recommended approach how to use a generic header file is to list the file in the Kbuild file. - See "7.4 generic-y" for further info on syntax etc. + See "7.3 generic-y" for further info on syntax etc. --- 6.11 Post-link pass @@ -1263,53 +1263,32 @@ The pre-processing does: - drop include of compiler.h - drop all sections that are kernel internal (guarded by ifdef __KERNEL__) -Each relevant directory contains a file name "Kbuild" which specifies the -headers to be exported. -See subsequent chapter for the syntax of the Kbuild file. - - --- 7.1 header-y - - header-y specifies header files to be exported. - - Example: - #include/linux/Kbuild - header-y += usb/ - header-y += aio_abi.h +All headers under include/uapi/, include/generated/uapi/, +arch/<arch>/include/uapi/ and arch/<arch>/include/generated/uapi/ +are exported. - The convention is to list one file per line and - preferably in alphabetic order. +A Kbuild file may be defined under arch/<arch>/include/uapi/asm/ and +arch/<arch>/include/asm/ to list asm files coming from asm-generic. +See subsequent chapter for the syntax of the Kbuild file. - header-y also specifies which subdirectories to visit. - A subdirectory is identified by a trailing '/' which - can be seen in the example above for the usb subdirectory. + --- 7.1 no-export-headers - Subdirectories are visited before their parent directories. + no-export-headers is essentially used by include/uapi/linux/Kbuild to + avoid exporting specific headers (e.g. kvm.h) on architectures that do + not support it. It should be avoided as much as possible. --- 7.2 genhdr-y - genhdr-y specifies generated files to be exported. - Generated files are special as they need to be looked - up in another directory when doing 'make O=...' builds. + genhdr-y specifies asm files to be generated. Example: - #include/linux/Kbuild - genhdr-y += version.h + #arch/x86/include/uapi/asm/Kbuild + genhdr-y += unistd_32.h + genhdr-y += unistd_64.h + genhdr-y += unistd_x32.h - --- 7.3 destination-y - When an architecture has a set of exported headers that needs to be - exported to a different directory destination-y is used. - destination-y specifies the destination directory for all exported - headers in the file where it is present. - - Example: - #arch/xtensa/platforms/s6105/include/platform/Kbuild - destination-y := include/linux - - In the example above all exported headers in the Kbuild file - will be located in the directory "include/linux" when exported. - - --- 7.4 generic-y + --- 7.3 generic-y If an architecture uses a verbatim copy of a header from include/asm-generic then this is listed in the file @@ -1336,7 +1315,7 @@ See subsequent chapter for the syntax of the Kbuild file. Example: termios.h #include <asm-generic/termios.h> - --- 7.5 generated-y + --- 7.4 generated-y If an architecture generates other header files alongside generic-y wrappers, and not included in genhdr-y, then generated-y specifies @@ -1349,6 +1328,15 @@ See subsequent chapter for the syntax of the Kbuild file. #arch/x86/include/asm/Kbuild generated-y += syscalls_32.h + --- 7.5 mandatory-y + + mandatory-y is essentially used by include/uapi/asm-generic/Kbuild.asm + to define the minimun set of headers that must be exported in + include/asm. + + The convention is to list one subdir per line and + preferably in alphabetic order. + === 8 Kbuild Variables The top Makefile exports the following variables: |