From aa8dbeee5ee012e1ee595dd1df9be04e161a3fd4 Mon Sep 17 00:00:00 2001 From: Yann Droneaud Date: Sun, 13 Jul 2014 12:15:29 +0200 Subject: Documentation: headers_install.txt is part of kbuild 'headers_install.txt' from Documentation/make/ is related to Kbuild so it must be moved in Documentation/kbuild/ directory. As Documentation/make/ directory has only one file, it will be removed as a consequence of moving 'headers_install.txt'. Cc: Kirill A. Shutemov Cc: David Woodhouse Cc: Rob Landley Signed-off-by: Yann Droneaud Acked-by: Sam Ravnborg Signed-off-by: Michal Marek --- Documentation/kbuild/00-INDEX | 2 ++ Documentation/kbuild/headers_install.txt | 47 ++++++++++++++++++++++++++++++++ 2 files changed, 49 insertions(+) create mode 100644 Documentation/kbuild/headers_install.txt (limited to 'Documentation/kbuild') diff --git a/Documentation/kbuild/00-INDEX b/Documentation/kbuild/00-INDEX index e8d2b6d83a3..8c5e6aa7800 100644 --- a/Documentation/kbuild/00-INDEX +++ b/Documentation/kbuild/00-INDEX @@ -1,5 +1,7 @@ 00-INDEX - this file: info on the kernel build process +headers_install.txt + - how to export Linux headers for use by userspace kbuild.txt - developer information on kbuild kconfig.txt diff --git a/Documentation/kbuild/headers_install.txt b/Documentation/kbuild/headers_install.txt new file mode 100644 index 00000000000..951eb9f1e04 --- /dev/null +++ b/Documentation/kbuild/headers_install.txt @@ -0,0 +1,47 @@ +Exporting kernel headers for use by userspace +============================================= + +The "make headers_install" command exports the kernel's header files in a +form suitable for use by userspace programs. + +The linux kernel's exported header files describe the API for user space +programs attempting to use kernel services. These kernel header files are +used by the system's C library (such as glibc or uClibc) to define available +system calls, as well as constants and structures to be used with these +system calls. The C library's header files include the kernel header files +from the "linux" subdirectory. The system's libc headers are usually +installed at the default location /usr/include and the kernel headers in +subdirectories under that (most notably /usr/include/linux and +/usr/include/asm). + +Kernel headers are backwards compatible, but not forwards compatible. This +means that a program built against a C library using older kernel headers +should run on a newer kernel (although it may not have access to new +features), but a program built against newer kernel headers may not work on an +older kernel. + +The "make headers_install" command can be run in the top level directory of the +kernel source code (or using a standard out-of-tree build). It takes two +optional arguments: + + make headers_install ARCH=i386 INSTALL_HDR_PATH=/usr/include + +ARCH indicates which architecture to produce headers for, and defaults to the +current architecture. The linux/asm directory of the exported kernel headers +is platform-specific, to see a complete list of supported architectures use +the command: + + ls -d include/asm-* | sed 's/.*-//' + +INSTALL_HDR_PATH indicates where to install the headers. It defaults to +"./usr/include". + +The command "make headers_install_all" exports headers for all architectures +simultaneously. (This is mostly of interest to distribution maintainers, +who create an architecture-independent tarball from the resulting include +directory.) You also can use HDR_ARCH_LIST to specify list of architectures. +Remember to provide the appropriate linux/asm directory via "mv" or "ln -s" +before building a C library with headers exported this way. + +The kernel header export infrastructure is maintained by David Woodhouse +. -- cgit v1.2.3-70-g09d2