Diffstat (limited to 'Documentation/make/headers_install.txt')
1 files changed, 47 insertions, 0 deletions
diff --git a/Documentation/make/headers_install.txt b/Documentation/make/headers_install.txt
new file mode 100644
@@ -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
+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
+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
+ 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
+ ls -d include/asm-* | sed 's/.*-//'
+INSTALL_HDR_PATH indicates where to install the headers. It defaults to
+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