Are the Xilinx PCI/PCI-X cores capable of implementing a CompactPCI HotSwap solution?
You can use the PCI and PCI-X LogiCOREs in CompactPCI HotSwap applications. However, it is important to review the appropriate device data sheets since the ability to perform a HotSwap is a silicon issue and not a core issue. There are no functional differences between normal PCI and CompactPCI HotSwap applications.
HotSwap is an extension of the CompactPCI specification that allows for the removal and insertion of cards without removing power from the bus. This is important to the telecom and networking industries because it allows the implementation of High Availability systems, in which repairs and upgrades are performed without down time.
Do not confuse HotSwap with Hotplug, which is a PCI initiative. Hotplug is only applicable to the regular PCI form factor and requires powering down the slot. HotSwap does not require the slot to be powered down.
The logical implementation of a CompactPCI interface in its basic form (non-HotSwap) is no different than a comparable standard PCI implementation. Some differences do exist in the board-level implementation. The CompactPCI HotSwap specification defines three levels of HotSwap boards and three levels of HotSwap systems:
For HotSwap implementations, the HotSwap Register Block must be implemented in user-configuration space as a capabilities list item. The HotSwap Register Block is described in Chapter 7.2 of the CompactPCI HotSwap Specification PICMG 2.1 R2.0. After implementing the user-configuration space register and the associated functionality, link the capability list item into the capabilities list by adjusting the capabilities pointer and/or the next item pointer of other capabilities list items. User-configuration space and the capabilities pointer are described in the design guide shipped with the Xilinx interface.
There are no differences between the non-HotSwap CompactPCI device electrical specifications and standard PCI electrical specifications. However, CompactPCI places a number of additional specifications on the actual board implementation. You must obtain and carefully read the implementation instructions provided in the relevant PICMG documents to ensure implementation compliance.
For HotSwap implementations, the implementation technology must provide low quiescent leakage current. Silicon requirements are described in Chapter 7.1 of the CompactPCI HotSwap Specification PICMG 2.1 R2.0. Most FPGA devices supported by this Xilinx interface support HotSwap implementations.
Consult the relevant FPGA device data sheet for additional information on leakage current and how to disable the device I/O pullups before and during the FPGA device configuration process. The device data sheets are at:
The PCI and PCI-X LogiCOREs are shipped with a document in the "docs" directory that further describes using the Xilinx Cores with HotSwap applications. This document is also outlined in solution (Xilinx Answer 17126).
More information on Hot-Swapping with Virtex, Virtex-E, Virtex-II and Spartan-IIE devices is available in (Xilinx Answer 6768).