cross-ng: document host dependencies for kernel cross compilation

chapter02/hostreqs.xml

@@ -34,6 +34,11 @@
       not been tested)</para>
     </listitem>
 
+    <listitem>
+      <!-- needed to cross build the kernel in chapter 6 -->
+      <para><emphasis role="strong">Bc-1.07.0</emphasis></para>
+    </listitem>
+
     <listitem>
       <para><emphasis role="strong">Bison-2.7</emphasis> (/usr/bin/yacc
       should be a link to bison or small script that executes bison)</para>
@@ -139,6 +144,7 @@ echo "/bin/sh -&gt; $MYSH"
 echo $MYSH | grep -q bash || echo "ERROR: /bin/sh does not point to bash"
 unset MYSH
 
+bc --version | head -n1
 echo -n "Binutils: "; ld --version | head -n1 | cut -d" " -f3-
 bison --version | head -n1
 

chapter06/kernel.xml

@@ -168,14 +168,26 @@
       </varlistentry>
 
       <varlistentry>
-        <term>Enable <parameter>CONFIG_EXT2</parameter>,
-                     <parameter>CONFIG_EXT4</parameter>,
-                 and <parameter>CONFIG_VFAT_FS</parameter></term>
+        <term>Set <parameter>CONFIG_EXT2=y</parameter>,
+                  <parameter>CONFIG_EXT4=y</parameter>,
+              and <parameter>CONFIG_VFAT_FS=y</parameter></term>
         <listitem>
           <para>They are needed to access the filesystems we'll make for the
           target system.</para>
         </listitem>
       </varlistentry>
+
+      <varlistentry>
+        <term>Set <parameter>CONFIG_MODULE_SIG=n</parameter>,
+                  <parameter>CONFIG_SECURITY=n</parameter>,
+              and <parameter>CONFIG_STACK_VALIDATION=n</parameter></term>
+        <listitem>
+          <para>They are unneeded for the temporary kernel, and they need
+          additional dependencies which may be unavailable on the host
+          distro. You can enable them building the kernel for the final LFS
+          system in Chapter 10 if you need these features.</para>
+        </listitem>
+      </varlistentry>
     </variablelist>
 
     <para>Compile the kernel image:</para>