Prior to using the IAP service, it may be required to first validate the new bitstream before committing the device to reprogramming, thus avoiding the need to invoke recovery procedures if the bitstream is invalid.
The bitstream authentication service analyzes a bitstream image stored in SPI Flash and checks for all conditions which may result in an authentication error. While the authentication is in progress, the user design continues to operate normally, but without access to SPI Flash and system services until the authentication process is complete.
If the authentication service is called while a new bitstream is being loaded through the JTAG interface, the system service takes precedence and the JTAG interface is stalled during the authentication and will ultimately fail.
| System Service Descriptor Bit Field | Value | Description |
|---|---|---|
| 15:7 | MBOXADDR[10:2] | Mailbox address. See Table 2. |
| 6:0 | 23H | Bitstream authentication service command. |
The following table lists the bitstream authentication service mailbox format.
| Offset | Length (bytes) | Parameter | Direction | Description |
|---|---|---|---|---|
| 0 | 4 | SPIADDR | Input | Address of the bitstream in SPI Flash. If the external SPI Flash device does not support 32-bit addresses, SPIADDR[31:24] is ignored. |