mirror of https://github.com/tLDP/LDP
43 lines
2.0 KiB
XML
43 lines
2.0 KiB
XML
<sect2><title> </title><para> </para></sect2>
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<sect2>
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<title>Why we copy the kernel headers and don't symlink them</title>
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<para>In the past it was common practice to symlink the
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<filename class="directory">/usr/include/{linux,asm}</filename> directories
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to <filename class="directory">/usr/src/linux/include/{linux,asm}</filename>.
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This was a <emphasis>bad</emphasis> practice, as the following extract from a
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post by Linus Torvalds to the Linux Kernel Mailing List points out:</para>
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<screen>I would suggest that people who compile new kernels should:
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- not have a single symbolic link in sight (except the one that the
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kernel build itself sets up, namely the "linux/include/asm" symlink
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that is only used for the internal kernel compile itself)
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And yes, this is what I do. My /usr/src/linux still has the old 2.2.13
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header files, even though I haven't run a 2.2.13 kernel in a _loong_
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time. But those headers were what Glibc was compiled against, so those
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headers are what matches the library object files.
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And this is actually what has been the suggested environment for at
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least the last five years. I don't know why the symlink business keeps
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on living on, like a bad zombie. Pretty much every distribution still
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has that broken symlink, and people still remember that the linux
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sources should go into "/usr/src/linux" even though that hasn't been
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true in a _loong_ time.</screen>
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<para>The essential part is where Linus states that the header files should be
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<emphasis>the ones which Glibc was compiled against</emphasis>. These are
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the headers that should be used when you later compile other packages, as they
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are the ones that match the object-code library files. By copying the headers,
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we ensure that they remain available if later you upgrade your kernel.</para>
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<para>Note, by the way, that it is perfectly all right to have the kernel sources
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in <filename class="directory">/usr/src/linux</filename>, as long as you don't
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have the <filename class="directory">/usr/include/{linux,asm}</filename>
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symlinks.</para>
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</sect2>
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