Date: Sun, 13 Jan 2013 06:11:31 +0000 (UTC) From: Eitan Adler <eadler@FreeBSD.org> To: doc-committers@freebsd.org, svn-doc-all@freebsd.org, svn-doc-head@freebsd.org Subject: svn commit: r40602 - head/en_US.ISO8859-1/books/faq Message-ID: <201301130611.r0D6BVNb031853@svn.freebsd.org>
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Author: eadler Date: Sun Jan 13 06:11:30 2013 New Revision: 40602 URL: http://svnweb.freebsd.org/changeset/doc/40602 Log: Update and expand on the why-kernel-big question in the handbook. PR: docs/174244 Submitted by: Bas Smeelen <b.smeelen@ose.nl> Approved by: bcr (mentor) Modified: head/en_US.ISO8859-1/books/faq/book.xml Modified: head/en_US.ISO8859-1/books/faq/book.xml ============================================================================== --- head/en_US.ISO8859-1/books/faq/book.xml Sun Jan 13 06:09:00 2013 (r40601) +++ head/en_US.ISO8859-1/books/faq/book.xml Sun Jan 13 06:11:30 2013 (r40602) @@ -3297,17 +3297,27 @@ kern.timecounter.hardware: TSC -> i82 </question> <answer> - <para>Chances are, you compiled your kernel in <emphasis>debug - mode</emphasis>. Kernels built in debug mode contain many - symbols that are used for debugging, thus greatly increasing - the size of the kernel. Note that there will be little or - no performance decrease from running a debug kernel, and it - is useful to keep one around in case of a system - panic.</para> - - <para>However, if you are running low on disk space, or you - simply do not want to run a debug kernel, make sure that - both of the following are true:</para> + <para>GENERIC kernels shipped with &os; and later are compiled + in <emphasis>debug mode</emphasis>. Kernels built in debug mode + contain many symbols in separate files that are used for + debugging, thus greatly increasing the size of + <filename class="directory">/boot/kernel/</filename> + Note that there will be little or no performance loss + from running a debug kernel, and it is useful to keep one around + in case of a system panic.</para> + + <para>However, if you are running low on disk space, there are + different options to reduce the size of /boot/kernel/.</para> + + <para>If you do not want the symbol files to be installed, + make sure you have the following line present in /etc/src.conf: + + <programlisting>WITHOUT_KERNEL_SYMBOLS=yes</programlisting> + + For more information see &man.src.conf.5</para> + + <para>If you do not want to build a debug kernel, make + sure that both of the following are true:</para> <itemizedlist> <listitem> @@ -3325,9 +3335,32 @@ kern.timecounter.hardware: TSC -> i82 <para>Either of the above settings will cause your kernel to be built in debug mode. As long as you make sure you follow - the steps above, you can build your kernel normally, and you - should notice a fairly large size decrease; most kernels - tend to be around 1.5 MB to 2 MB.</para> + the steps above, you can build your kernel normally</para> + + <para>If you want only the modules you use to be built + and installed, make sure you have a line like below in + /etc/make.conf:</para> + + <programlisting>MODULES_OVERRIDE= <replaceable>accf_http ipfw</replaceable></programlisting> + + <para>Replace <emphasis>accf_httpd ipfw</emphasis> with a list + of modules you need. Only these modules will be built. This + does not only reduce the size of the kernel directory but + also decreases the amount of time needed to build your kernel. + For more information see + <filename>/usr/share/examples/etc/make.conf</filename> + </para> + + <para>You can also remove unneeded devices from your kernel + to further reduce the size. See + <xref linkend="make-kernel"/> for more information.</para> + + <para>To put any of these options into effect you will have + to <ulink url="&url.books.handbook;/kernelconfig-building.html">build and install</ulink> + your new kernel.</para> + + <para>Most kernels (/boot/kernel/kernel) + tend to be around 12 MB to 16 MB.</para> </answer> </qandaentry>
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