README.hardware: extend USB-ZIP instructions

* Note that on some machines booting just stops after the SYSLINUX
  version banner is displayed
* Add an instruction to show how to get the geometry information for
  the disk
* Specify the number of cylinders when running mkdiskimage as it is
  sometimes unable to detect it automatically
* Create the temporary mountpoints before attempting to use them
* Add an instruction to unmount the disk before removing it

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

README.hardware

@@ -96,8 +96,9 @@ USB Device:
 
      # dd if=core-image-minimal-atom-pc.hddimg of=/dev/sdb
 
-  If the device fails to boot with "Boot error" displayed, it is likely the BIOS
-  cannot understand the physical layout of the disk (or rather it expects a
+  If the device fails to boot with "Boot error" displayed, or apparently
+  stops just after the SYSLINUX version banner, it is likely the BIOS cannot
+  understand the physical layout of the disk (or rather it expects a
   particular layout and cannot handle anything else). There are two possible
   solutions to this problem:
 
@@ -106,26 +107,47 @@ USB Device:
      geometry from the device.
 
   2. Without such an option, the BIOS generally boots the device in USB-ZIP
-     mode.
+     mode. To write an image to a USB device that will be bootable in
+     USB-ZIP mode, carry out the following actions:
 
-     a. Configure the USB device for USB-ZIP mode:
+     a. Determine the geometry of your USB device using fdisk:
+
+     # fdisk /dev/sdb
+     Command (m for help): p
+
+     Disk /dev/sdb: 4011 MB, 4011491328 bytes
+     124 heads, 62 sectors/track, 1019 cylinders, total 7834944 sectors
+     ...
+
+     Command (m for help): q
+
+     b. Configure the USB device for USB-ZIP mode:
      
-     # mkdiskimage -4 /dev/sdb 0 63 62
+     # mkdiskimage -4 /dev/sdb 1019 124 62
 
-     Where 63 and 62 are the head and sector count as reported by fdisk.
-     Remove and reinsert the device to allow the kernel to detect the new
-     partition layout.
+     Where 1019, 124 and 62 are the cylinder, head and sectors/track counts
+     as reported by fdisk (substitute the values reported for your device).
+     When the operation has finished and the access LED (if any) on the
+     device stops flashing, remove and reinsert the device to allow the
+     kernel to detect the new partition layout.
 
-     b. Copy the contents of the poky image to the USB-ZIP mode device:
+     c. Copy the contents of the poky image to the USB-ZIP mode device:
 
+     # mkdir /tmp/image
+     # mkdir /tmp/usbkey
      # mount -o loop core-image-minimal-atom-pc.hddimg  /tmp/image
      # mount /dev/sdb4 /tmp/usbkey
      # cp -rf /tmp/image/* /tmp/usbkey
 
-     c. Install the syslinux boot loader:
+     d. Install the syslinux boot loader:
 
      # syslinux /dev/sdb4
 
+     e. Unmount everything:
+
+     # umount /tmp/image
+     # umount /tmp/usbkey
+
   Install the boot device in the target board and configure the BIOS to boot
   from it.