Attachment 63297 Details for Bug 94454 – faq.diff

[patch] faq.diff

faq.diff (text/plain), 2.12 KB, created by Bill Moran on 2006-03-14 21:40:16 UTC

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Creator: Bill Moran

Created: 2006-03-14 21:40:16 UTC

Size: 2.12 KB

patch

obsolete

>--- book.sgml.old	Tue Mar 14 16:28:40 2006
>+++ book.sgml	Tue Mar 14 16:27:34 2006
>@@ -2871,6 +2871,45 @@
> 
>     <qandaset>
>       <qandaentry>
>+        <question id="pae">
>+          <para>Why is &os; finding the wrong amount of memory?</para>
>+        </question>
>+
>+        <answer>
>+          <para>The reason is the difference between physical memory
>+            addresses and virtual addresses.</para>
>+
>+          <para>The convention for most PC hardware is to use memory
>+            between 3.5G and 4G for special use (usually for PCI).
>+            This is physical memory address space that is used to access
>+            the PCI hardware.  As a result real memory (RAM) can not
>+            exist there.</para>
>+
>+          <para>What happens to the memory that should appear in that
>+            location is dependent on your hardware.  Unfortunately,
>+            some hardware does nothing and the ability to use that
>+            last 500M of RAM is lost.</para>
>+
>+          <para>Luckily, most hardware remaps the memory to a higher
>+            location so that it can still be used.  However, this can
>+            cause some confusion if you watch the boot messages.</para>
>+
>+          <para>On a 32 bit version of &os;, the memory appears lost,
>+            since it will be remapped above 4G, which a 32 bit kernel
>+            is unable to access.  In this case, the solution is to
>+            build a PAE enabled kernel.  See
>+            <link linkend="memory-limits">this FAQ entry</link> for
>+            more information.</para>
>+            
>+          <para>On a 64 bit version of &os;, or when running a PAE-enabled
>+            kernel, &os; will correctly detect and remap the memory so
>+            it is usable.  During boot, however, it may seem as if &os;
>+            is detecting more memory than the system really has.  This
>+            is normal and the available memory will be corrected as the
>+            boot process completes.<para>
>+        </answer>
>+      </qandaentry>
>+      <qandaentry>
>         <question id="awre">
>           <para>What do I do when I have bad blocks on my hard drive?</para>
>         </question>

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