Answers Database
LogiCORE PCI: How does the LogiCORE interface handle target abort?
Record #5227
Product Family: Documentation
Product Line: PCI Apps
Product Part: PCI Frequently Asked Questions
Problem Title:
LogiCORE PCI: How does the LogiCORE interface handle target abort?
Problem Description:
Urgency: Standard
General Description:
How does the LogiCORE interface handle target abort?
Solution 1:
A target may request an abnormal termination if it detects a
fatal error or if it will never will be able to complete the
request. This is known as a target abort. A target abort may
cause a fatal error for the user application, but the
transaction completes gracefully, thus, preserving normal
operation for other agents.
The target abort termination can only occur after the DEVSEL#
line has been asserted for at lease one clock cycle. The target
signals target abort by deasserting DEVSEL# and asserting STOP#
at the same time. Target abort can occur whether or not data is
being accessed.
A target abort signals to the present PCI master that it should
not repeat the same COMMAND type to the same address (target).
It can try a different COMMAND type.
The LogiCORE PCI interface deasserts the FRAME_IO signal after
receiving a target abort (asserts STOP_IO). The user application
can cause the LogiCORE target interface to signal a target
abort and set the 'signaled target abort bit (CSR 27)' in the
status register by asserting the T_ABORT signal.
A LogiCORE initiator will set the 'received target abort bit
(CSR 28)' when it detects that an addressed target signaled a
target abort.
The 'target signaled abort bit (CSR38) is set after the target
signals an abort condition.
End of Record #5227 - Last Modified: 10/01/99 11:32 |
