Like anything that can be useful on a Debian system, the Linux kernel sources are available in a package. To retrieve them, just install the <emphasis role="pkg">linux-source-<replaceable>version</replaceable></emphasis> package. The <command>apt-cache search ^linux-source</command> command lists the various kernel versions packaged by Debian. The latest version is available in the <emphasis role="distribution">Unstable</emphasis> distribution: you can retrieve them without much risk (especially if your APT is configured according to the instructions of <xref linkend="sect.apt-mix-distros" />). Note that the source code contained in these packages does not correspond precisely with that published by Linus Torvalds and the kernel developers; like all distributions, Debian applies a number of patches, which might (or might not) find their way into the upstream version of Linux. These modifications include backports of fixes/features/drivers from newer kernel versions, new features not yet (entirely) merged in the upstream Linux tree, and sometimes even Debian specific changes.
-cachesearch ^linux-source</command> command lists the various kernel versions packaged by Debian. The latest version is available in the <emphasis role="distribution">Unstable</emphasis> distribution: you can retrieve them without much risk (especially if your APT is configured according to the instructions of <xref linkend="sect.apt-mix-distros" />). Note that the source code contained in these packages does not correspond precisely with that published by Linus Torvalds and the kernel developers; like all distributions, Debian applies a number of patches, which might (or might not) find their way into the upstream version of Linux. These modifications include backports of fixes/features/drivers from newer kernel versions, new features not yet (entirely) merged in the upstream Linux tree, and sometimes even Debian specific changes.