The WBSTAR (Warm Boot Start Address) register holds the
address that the configuration controller uses after an IPROG command is
issued. This can be either in the form of an address, or values for the RS
pins in BPI mode. This register can be loaded from bitstream options or from the ICAP. If the
register is not set in the bitstream options, it is loaded with a default value of
0s. Therefore, after the golden image sets the WBSTAR value and initiates a
multiboot configuration, the multiboot pattern resets the WBSTAR to 0 by
default.
At power-up, the device issues the read command to the
flash followed by a start address of 0. After the WBSTAR command has been
loaded and the IPROG command is issued, the configuration controller issues
the read command from the address specified by the WBSTAR address.