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diff --git a/chapter06/kernel-exp-headers.xml b/chapter06/kernel-exp-headers.xml new file mode 100644 index 000000000..de1256f3c --- /dev/null +++ b/chapter06/kernel-exp-headers.xml @@ -0,0 +1,35 @@ +<sect2> +<title>Why we copy the kernel headers and don't symlink them</title> + +<para>In the past, it was common practice for people to symlink the +/usr/include/linux and asm directories to /usr/src/linux/include/linux +and asm respectively. This is a <emphasis>bad</emphasis> idea as +this extract from a post by Linus Torvalds to the Linux Kernel +Mailing List points out:</para> + +<screen>I would suggest that people who compile new kernels should: + + - not have a single symbolic link in sight (except the one that the + kernel build itself sets up, namely the "linux/include/asm" symlink + that is only used for the internal kernel compile itself) + +And yes, this is what I do. My /usr/src/linux still has the old 2.2.13 +header files, even though I haven't run a 2.2.13 kernel in a _loong_ +time. But those headers were what glibc was compiled against, so those +headers are what matches the library object files. + +And this is actually what has been the suggested environment for at +least the last five years. I don't know why the symlink business keeps +on living on, like a bad zombie. Pretty much every distribution still +has that broken symlink, and people still remember that the linux +sources should go into "/usr/src/linux" even though that hasn't been +true in a _loong_ time.</screen> + +<para>The relevant part here is where he states that the headers should +be the ones which <emphasis>glibc was compiled against</emphasis>. These are +the headers which should remain accessible and so by copying them, we ensure +that we follow these guidelines. Also note that as long as you don't have +those symlinks, it is perfectly fine to have the kernel sources +in <filename>/usr/src/linux</filename>.</para> + +</sect2> |