In order to enable it, #define HAVE_DUALBOOT when building the bootloader.
Do not use the automatically created x5_fw.bin or m5_fw.bin, but use mkboot
to create a new firmware file from an OF x5_fw.bin resp. m5_fw.bin and
bootloader.bin.
The dual-boot bootloader boots the OF when pressing Play (main or remote) for
more than 3 seconds. Hold it a bit longer because the OF also checks buttons.
Short press boots rockbox.
As a bonus, the Play button read (for hold check) is done a bit earlier for
single-boot mode as well.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30018 a1c6a512-1295-4272-9138-f99709370657
