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Add some information about PAE. This is not an in depth text.

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Requested by:	murray
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Tom Rhodes 2003-10-08 19:46:37 +00:00
parent 65ef3e6581
commit 4c830e44fa
Notes: svn2git 2020-12-08 03:00:23 +00:00 
svn path=/head/; revision=18363
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en_US.ISO8859-1/books/handbook/kernelconfig/chapter.sgml
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@ -1327,6 +1327,35 @@ pseudo-device bpf # Berkeley packet filter</programlisting>
<para>For more information and additional devices supported by
&os;, see
<filename>/usr/src/sys/i386/conf/LINT</filename>.</para>
<sect2>
<title>Defeating Memory Limitations</title>
<para>In the past, &os; never made use of memory beyond four
gigabytes. This was termed the four gigabyte limit and
was a hassle to those who owned machines which supported a
memory size larger than four gigabytes. For those users, the
&man.pae.4; driver was written. The <literal>PAE</literal>
driver provides for memory address extensions ultimately
permitting up to sixty-four gigabytes. To make use of this
feature, just add:</para>
<programlisting>options PAE</programlisting>
<para>to the kernel configuration file as explained above.</para>
<note>
<para>This option is slightly experimental, and could could cause
minor problems. For instance, the kernel's virtual address
space may need to be increased. Add the
<option>KVA_PAGES</option> from <filename>NOTES</filename> to
the kernel configuration file. The default number,
<literal>260</literal>, may need to be increased and the
<option>kern.maxvnodes</option> may need to be decreased by
using the <command>sysctl</command> utility. Reading the
&man.tuning.7; manual page is certainly advised.</para>
</note>
</sect2>
</sect1>
<sect1 id="kernelconfig-nodes">