documentation: Documentation/initrd.txt

From: Thomas Horsley <[email protected]>

I spent a long time the other day trying to examine an initrd image on a fedora core 5 system because the initrd.txt file is apparently obsolete. Here is a patch which I hope will reduce future confusion for others.

---

I'm resubmitting this according to the SubmittingPatches guidelines. This was made from the 2.6.17.7 tree, but I don't think initrd.txt has changed much in any of the trees. I know I'm not supposed to send an attachment, but I see evolution has already screwed up my cut and paste attempt and who knows what will happen by the time it goes through exchange, so I'm adding the patch as an attachment as well.

@@ -73,6 +73,22 @@
     initrd is mounted as root, and the normal boot procedure is

followed,
with the RAM disk still mounted as root.

+Compressed cpio images
+----------------------
+
+Recent kernels have support for populating a ramdisk from a compressed cpio
+archive, on such systems, the creation of a ramdisk image doesn't need to
+involve special block devices or loopbacks, you merely create a directory on
+disk with the desired initrd content, cd to that directory, and run (as an
+example):
+
+find . | cpio --quiet -c -o | gzip -9 -n > /boot/imagefile.img +
+Examining the contents of an existing image file is just as simple:
+
+mkdir /tmp/imagefile
+cd /tmp/imagefile
+gzip -cd /boot/imagefile.img | cpio -imd --quiet

Installation
------------

@@ -73,6 +73,22 @@
     initrd is mounted as root, and the normal boot procedure is followed,
     with the RAM disk still mounted as root.
 
+Compressed cpio images
+----------------------
+
+Recent kernels have support for populating a ramdisk from a compressed cpio
+archive, on such systems, the creation of a ramdisk image doesn't need to
+involve special block devices or loopbacks, you merely create a directory on
+disk with the desired initrd content, cd to that directory, and run (as an
+example):
+
+find . | cpio --quiet -c -o | gzip -9 -n > /boot/imagefile.img
+
+Examining the contents of an existing image file is just as simple:
+
+mkdir /tmp/imagefile
+cd /tmp/imagefile
+gzip -cd /boot/imagefile.img | cpio -imd --quiet
 
 Installation
 ------------