mtd/html/doc jffs2.xml,1.1,1.2

[havasi at infradead.org]

Update of /home/cvs/mtd/html/doc
In directory phoenix.infradead.org:/tmp/cvs-serv20262

Modified Files:
	jffs2.xml 
Log Message:
[JFFS2] Add Erase Block Summary documentation to the webpage



Index: jffs2.xml
===================================================================
RCS file: /home/cvs/mtd/html/doc/jffs2.xml,v
retrieving revision 1.1
retrieving revision 1.2
diff -u -r1.1 -r1.2
--- jffs2.xml	12 Mar 2005 13:48:22 -0000	1.1
+++ jffs2.xml	30 Sep 2005 08:49:33 -0000	1.2
@@ -55,6 +55,36 @@
       <tt>/proc/mtd</tt> if you don't know), and create your JFFS2
       image for it with the correct <tt>-e</tt> option.</p>
 
-		
+    <hr size="2" />
+    
+    <h2>Erase Block Summary (EBS)</h2>
+
+    <p>The goal of EBS is to speed up the mount process. 
+    It stores summary information at the end of every erase block. 
+    At mount time it is no longer necessary to scan all nodes individually 
+    (and read all pages of the erase blocks), enough to read this "small" 
+    summary.
+    </p>
+    
+    <p>This summary information is stored in a JFFS2_FEATURE_RWCOMPAT_DELETE
+    node. During mount process if there is no summary node at the end of
+    an erase block, the original scan process will be executed.
+    </p>
+    
+    <p>This node is generated automatically if EBS enabled for written
+    data, but you should also use the user space tool called sumtool 
+    to insert summary information after you created a JFFS2 image
+    with <tt>mkfs.jffs2</tt>. Example:
+    </p>
+    <div>
+<pre>
+mkfs.jffs2 -rdir -oout.jffs2 -e128KiB
+sumtool -iout.jffs2 -oout-sum.jffs2 -e128KiB
+</pre>
+    </div>
+    <p>EBS should work with NOR and NAND, too. The rate of speedup is
+    generally higher on NAND chips and on the chips where the erase 
+    block size is large.
+    </p>
 	<INCLUDE file="../inc/footer.tmpl" />
 </PAGE>