Method and system for sharing input/output devices
View Patent ↗A PCI-Express module that is coupled to plural host systems and to at least an input/output (I/O) device is provided. The PCI-Express module includes an upstream port module and a downstream port module that use a mapping table to facilitate the plural host systems sharing the I/O device by modifying a transaction layer packet (TLP) field. For upstream ID based traffic, a source identifier is replaced based on the mapping table and a destination identifier is replaced with a value that is captured during upstream port module initialization. For upstream address based traffic, the mapping table routes TLPs by using a downstream port number and a function number in a source identification field. For downstream ID based traffic, a destination identifier is replaced by using the mapping table for routing TLPs. For downstream address based traffic, the PCI-Express module uses an address map to route TLPs.
1. A network system, comprising:
a plurality of host systems; and
a shared PCI-Express module directly coupled to the plurality of host systems and to at least one shared input/output (I/O) device without using a PCI-Express switch and a PCI to PCI bridge such that each of the plurality of host system is unaware of the I/O device being shared among other host systems;
wherein the shared PCI-Express module includes an upstream port module communicating with the plurality of host systems, and a downstream port module communicating with the I/O device;
wherein the shared PCI-Express module receives a transaction layer packet (“TLP”), examines the TLP and based on a type of the TLP, routes the TLP by using either an identifier (“ID”) based routing that uses a bus, device and function number to specify a destination for the TLP or an address based routing that uses an address map for routing the TLP;
wherein when ID based routing is used to route the TLP to the shared I/O device, then a destination identifier field is modified by the shared PCI-Express module to match a function number;
wherein when ID based routing is used to route the TLP to one of the plurality of host systems, then a source identifier is modified by the shared PCI-Express module to include an upstream function number and a destination identifier is replaced with a value captured during an upstream port module initialization;
wherein ID based routing is used for a configuration type TLP that is used for configuring a device and a completion type TLP that indicates completion of a request; and address based routing is used for a memory request and an I/O request.
2. The system of claim 1 , wherein upstream address based traffic is routed by a address mapping table by using a downstream port number and a function number in a source identification field.
3. The system of claim 1 , wherein a vendor defined message is generated by the I/O device and sent to the PCI-Express module each time a PCI configuration Base Address Register is written, and the vendor defined message includes a function number and a base address that are used by a port for routing address based downstream traffic.
4. The system of claim 1 , wherein the PCI-Express module and the I/O device are part of a storage area network.
5. The system of claim 1 , wherein the I/O device is a host bus adapter.
6. A PCI-Express module operationally coupled to a plurality of host systems and to at least a shared input/output (I/O) device in a network, comprising:
an upstream port module communicating with the plurality of host systems for sharing the I/O device, such that each host system is unaware that the I/O device is being shared among the plurality of host systems, and
a downstream port module communicating with the I/O device;
wherein the PCI-Express module receives a transaction layer packet (“TLP”), examines the TLP and based on a type of the TLP, routes the TLP by using either an identifier (“ID”) based routing that uses a bus, device and function number to specify a destination for the TLP or an address based routing that uses an address map for routing the TLP;
wherein when ID based routing is used to route the TLP to the shared I/O device, then a destination identifier field is modified by the shared PCI-Express module to match a function number;
wherein when ID based routing is used to route the TLP to one of the plurality of host systems, then a source identifier is modified by the shared PCI-Express module to include an upstream function number and a destination identifier is replaced with a value captured during upstream port module initialization;
wherein ID based routing is used for a configuration type TLP that is used for configuring a device and a completion type TLP that indicates completion of a request; and address based routing is used for a memory request and an I/O request.
7. The PCI-Express Module of claim 6 , wherein upstream address based traffic is routed by a address mapping table by using a downstream port number and a function number in a source identification field.
8. The PCI-Express Module of claim 6 , wherein a vendor defined message is generated by the I/O device and sent to the PCI-Express module each time a PCI configuration Base Address Register is written, and the vendor defined message includes a function number and a base address that are used by a port for routing address based downstream traffic.
9. The PCI-Express module of claim 6 , wherein the I/O device is a host bus adapter.
10. A method for sharing an input/output (I/O) device between a plurality of host systems, comprising:
receiving a transaction layer packet (TLP);
wherein if the TLP is for downstream traffic, it is received by an upstream port module of a PCI-Express module from one of the host systems; and if the TLP is for upstream traffic, it is received by a downstream port module of the PCI-Express Module from the I/O device; and
wherein the PCI-Express module is directly coupled to the plurality of host systems and to the I/O device without using a PCI-Express switch and a PCI to PCI bridge such that each of the plurality of host system is unaware of the I/O device being shared among the plurality of host systems; and
based on a type of the TLP, determining if an address based routing that uses an address map for routing the TLP or an identifier (ID) based routing technique that uses a bus, device and function number to specify a destination for the TLP is to be used for routing the TLP; wherein ID based routing is used for a configuration type TLP that is used for configuring a device and a completion type TLP that indicates completion of a request; and address based routing is used for a memory request and an I/O request;
wherein when ID based routing is used to route the TLP to the I/O device, then a destination identifier field is modified by the PCI-Express module to match a function number;
wherein when ID based routing is used to route the TLP to one of the plurality of host systems, then a source identifier is modified by the PCI-Express module to include an upstream function number and a destination identifier is replaced with a value captured during upstream port module initialization; and wherein an address mapping table is used for address based routing.
11. The method of claim 10 , wherein upstream address based traffic is routed by the address mapping table by using a downstream port number and a function number in a source identification field.
12. The method of claim 10 , wherein a vendor defined message is generated by the I/O device and sent to the PCI-Express module each time a PCI configuration Base Address Register is written, and the vendor defined message includes a function number and a base address that are used by a port for routing address based downstream traffic.
13. The method of claim 10 , wherein the I/O device is a host bus adapter.