docs: clarify that the boot requires a particular FS layout on the USB flash disk
Change-Id: I5b4c812ab6c97f3ac5e7aa20793b5a22ff987226
Suggested-by: Michal Hažlinský <hazlinsky@cesnet.cz>
diff --git a/README.md b/README.md
index 07543c1..23c27fc 100644
--- a/README.md
+++ b/README.md
@@ -80,7 +80,9 @@
```sh
./host/bin/kwboot -b ./u-boot-spl.kwb -t -p /dev/ttyUSB0
```
-Once in U-Boot, plug a USB flash disk which contains `images/usb-flash.img` and execute:
+Prepare a USB flash disk with a raw bootable image, `images/usb-flash.img`.
+Use a tool such as `dd` to overwrite the raw block device, do not copy the image file.
+Once in U-Boot, plug the USB flash disk and execute:
```sh
usb start; fatload usb 0:1 00800000 boot.scr; source 00800000