diff --git a/README.md b/README.md
index b892dd5..0621480 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,14 @@ This is a set of scripts for patching a Chrome OS RMA shim to serve as a bootloa
 ## Current Development Roadmap:
 - ~~build the image automatically~~
 - ~~boot to a shell~~
-- switch_root into an actual rootfs
-- start X11 in the actual rootfs
-- ui improvements in the bootloader
\ No newline at end of file
+- ~~switch_root into an actual rootfs~~
+- ~~start X11 in the actual rootfs~~
+- ~~ui improvements in the bootloader~~
+- load all needed drivers
+- autostart X11
+
+## Usage:
+1. Grab a Chrome OS RMA Shim from somewhere. Most of them have already been leaked and aren't too difficult to find.
+2. Download a Devuan live ISO. Run it inside a VM and install it to a disk image. Mount the disk image in the host.
+3. Run `sudo DEBUG=1 ./build.sh`. The `rootfs_dir` argument should point to where you mounted the rootfs in part 2.
+4. Flash the generated image to a USB drive or SD card.
\ No newline at end of file
diff --git a/build.sh b/build.sh
index d5fd7f1..f8c699d 100755
--- a/build.sh
+++ b/build.sh
@@ -88,7 +88,11 @@ echo "patching initramfs"
 patch_initramfs $initramfs_dir
 
 echo "creating disk image"
-create_image $output_path 20 1200
+rootfs_size=$(du -sm $rootfs_dir | cut -f 1)
+rootfs_part_size=$(($rootfs_size * 11 / 10 + 10))
+#create a 20mb bootloader partition
+#rootfs partition is 10% larger than its contents
+create_image $output_path 20 $rootfs_part_size
 
 echo "creating loop device for the image"
 image_loop=$(create_loop ${output_path})