When generating a Legacy Interrupt, the Endpoint Block Plus Wrapper does not set the Interrupt Status bit within the Device Status register. Why?
The interrupt status bit is bit 3 of the Device Status Register, located at Offset 06H in the Endpoints Type0 configuration space. This bit should be set when a legacy interrupt is generated to indicate that an interrupt is pending internally in the device. The Endpoint Block Plus solution does not set this bit correctly when the application generates a legacy interrupt on the CFG interface.
The system software uses this bit to identify the interrupting device in a scenario where multiple interrupt vectors are collapsed upstream.
There is no work-around at this time. However, this issue has not been known to cause any system problems by customers.
The v1.11 release User Guide now includes a note on this issue in the Interrupt Generation section.
Revision History 06/24/2009 - Update that v1.11 UG includes information 04/13/2009 - Update for ISE 11.1 release 09/10/2008 - Updated to reflect v1.9. 07/14/2008 - Changed title. 06/18/2008 - Initial Release of AR.