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47 lines
2.2 KiB
47 lines
2.2 KiB
Exporting kernel headers for use by userspace |
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The "make headers_install" command exports the kernel's header files in a |
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form suitable for use by userspace programs. |
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The linux kernel's exported header files describe the API for user space |
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programs attempting to use kernel services. These kernel header files are |
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used by the system's C library (such as glibc or uClibc) to define available |
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system calls, as well as constants and structures to be used with these |
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system calls. The C library's header files include the kernel header files |
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from the "linux" subdirectory. The system's libc headers are usually |
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installed at the default location /usr/include and the kernel headers in |
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subdirectories under that (most notably /usr/include/linux and |
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/usr/include/asm). |
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Kernel headers are backwards compatible, but not forwards compatible. This |
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means that a program built against a C library using older kernel headers |
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should run on a newer kernel (although it may not have access to new |
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features), but a program built against newer kernel headers may not work on an |
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older kernel. |
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The "make headers_install" command can be run in the top level directory of the |
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kernel source code (or using a standard out-of-tree build). It takes two |
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optional arguments: |
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make headers_install ARCH=i386 INSTALL_HDR_PATH=/usr/include |
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ARCH indicates which architecture to produce headers for, and defaults to the |
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current architecture. The linux/asm directory of the exported kernel headers |
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is platform-specific, to see a complete list of supported architectures use |
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the command: |
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ls -d include/asm-* | sed 's/.*-//' |
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INSTALL_HDR_PATH indicates where to install the headers. It defaults to |
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"./usr/include". |
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The command "make headers_install_all" exports headers for all architectures |
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simultaneously. (This is mostly of interest to distribution maintainers, |
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who create an architecture-independent tarball from the resulting include |
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directory.) You also can use HDR_ARCH_LIST to specify list of architectures. |
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Remember to provide the appropriate linux/asm directory via "mv" or "ln -s" |
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before building a C library with headers exported this way. |
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The kernel header export infrastructure is maintained by David Woodhouse |
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<dwmw2@infradead.org>.
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