# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1331339024 -3600
# Node ID b5baae9e31c9b4266fdb044da0fbd37cdadb504f
# Parent  d355c7a795140155097795c16ec0acd0aabb48f7
Added some User Mode Linux initrd notes.

diff -r d355c7a79514 -r b5baae9e31c9 README.txt
--- a/README.txt	Sat Mar 10 00:54:42 2012 +0100
+++ b/README.txt	Sat Mar 10 01:23:44 2012 +0100
@@ -9,6 +9,12 @@
 program environments, library paths, and so on. In effect, userinstall
 provides a personal package manager.
 
+In addition, userinstall also provides tools to manage conventional chroot
+filesystem areas and User Mode Linux system images. Such capabilities are
+useful when needing to run distributions that are sufficiently different from
+the host system's distribution that the non-root approach no longer works,
+due to system library or kernel incompatibilities.
+
 Contact, Copyright and Licence Information
 ------------------------------------------
 
@@ -45,7 +51,9 @@
     installations. Added --dev option for bind mounting of /dev in normal
     chroot installations.
   * Added support for UML instance construction from distribution
-    installations, along with networking support and a uml-net script.
+    installations, along with networking support and a uml-net script. Also
+    added some support for booting from initrd files and installation media
+    image files.
 
 Configuration
 -------------
@@ -295,6 +303,38 @@
 
 uml-do 512M --net
 
+Booting into UML from Installation Media
+----------------------------------------
+
+Instead of populating a filesystem image for User Mode Linux from an existing
+distribution installation, blank images can be created as follows:
+
+uml-make-image --do-not-populate 4 512
+
+Then, an initrd file can be used together with installation media - typically
+an ISO file that would usually be burned onto a CD or DVD - such that a UML
+instance can be booted and a distribution then installed into the blank images
+from the installation media.
+
+The initrd file is typically extracted from an ISO file (for example,
+installer.iso) as follows (with superuser privileges):
+
+mkdir installer
+mount -o loop installer.iso installer
+cp installer/initrd.gz .
+umount installer
+
+This assumes that initrd.gz is found at the top level of the installation
+media's filesystem.
+
+The UML instance is then booted as follows:
+
+uml-do 512M --net --initrd initrd.gz installer.iso
+
+The blank images will appear as /dev/ubda and /dev/ubdb devices in the
+instance, not merely as partitions, and so installers may ask you if you would
+like to partition these devices still further.
+
 Issues with Shared Memory
 -------------------------