Simulation of a PCI device`s memory
Contents
1. 718 a removable or non removable interface is typically used such as interface 726 It is to be appreciated that FIG 7 describes software that acts as an intermediary between users and the basic com puter resources described in suitable operating environment 710 Such software includes an operating system 728 Oper ating system 728 which can be stored on disk storage 724 acts to control and allocate resources of the computer system 712 System applications 730 take advantage of the man agement of resources by operating system 728 through program modules 732 and program data 734 stored either in system memory 716 or on disk storage 724 It is to be appreciated that the present invention can be implemented with various operating systems or combinations of operating systems A user enters commands or information into the computer 712 through input device s 736 Input devices 736 include but are not limited to a pointing device such as a mouse trackball stylus touch pad keyboard microphone joystick game pad satellite dish scanner TV tuner card digital camera digital video camera web camera and the like These and other input devices connect to the processing unit 714 through the system bus 718 via interface port s 738 Interface port s 738 include for example a serial port a parallel port a game port and a universal serial bus USB Output device s 740 use some of the same type of ports as input device s 736 Thus f2. U S Patent Dec 26 2006 Sheet 3 of 7 US 7 155 379 B2 300 PCI Header E ass us 310 310 310 310 310 310 Base Address Register 5 Subsystem Vendor Device ID ROM Base Address Register Reserved Cap Ptr Max Interrupt Interrupt FIG 3 U S Patent Dec 26 2006 Sheet 4 of 7 US 7 155 379 B2 400 PCI SIMULATION 100 COMPONENT INITIALIZATION 110 DEVICE DRIVER COMPONENT ASSOCIATED WITH SIMULATED PCI CONFIGURATION DEVICE SPACE SIMULATOR 120 MEMORY MAPPED 130 VO SPACE SIMULATOR 430 PCI DRIVER 440 PLUG AND PLAY MANAGER OPERATING SYSTEM 200 FIG 4 U S Patent Dec 26 2006 Sheet 5 of 7 START CLAIM AN AMOUNT OF MEMORY IDENTIFY AT LEAST SOME OF THE CLAIMED MEMORY AS RESIDING ON A PCI BUS IDENTIFY A SIMULATED PCi DEVICE TO AN OPERATING SYSTEM EMPLOY AT LEAST SOME OF THE CLAIMED MEMORY AS SIMULATED MEMORY MAPPED I O REGISTERS OF THE SIMULATED PCI DEVICE LOAD A DEVICE DRIVER ASSOCIATED WITH THE SIMULATED PCI DEVICE INSTANTIATE A THREAD THAT MONITORS THE SIMULATED MEMORY MAPPED I O REGISTERS FOR A CHANGE IN ORDER TO SIMULATE BEHAVIOR OF THE SIMULATED PCI DEVICE INSTANTIATE A THREAD THAT CHANGES AT LEAST ONE OF THE SIMULATED MEMORY MAPPED I O REGISTERS IN ORDER TO SIMULATE BEHAVIOR OF THE SIMULATED PCI DEVICE END US 7 155 379 B2 500 d 510 520 530 540 550
3. O registers comprising executing on a computer processor the following com puter executable acts comprising claiming an amount of memory identifying the claimed memory as residing on a PCI bus identifying a simulated PCI device to an operating sys tem and 5 10 15 20 25 30 35 40 45 50 14 employing the claimed memory as simulated memory mapped I O registers of the simulated PCI device wherein identification of the claimed memory as residing on a PCI bus being based upon modification of an ACPI BIOS Differentiated System Description Table in order to represent the claimed memory as being part of a root of a PCI bus hierarchy 13 The method of claim 12 further comprising at least one of the following acts instantiating a thread that monitors the simulated memory mapped I O registers for a change in order to simulate behavior of the simulated PCI device instantiating a thread that changes at least one of the simulated memory mapped I O registers in order to simulate behavior of the simulated PCI device and loading a device driver associated with the simulated PCI device 14 The method of claim 12 identification of the simu lated PCI device to the operating system being based upon simulation of contents of PCI configuration space associated with the simulated PCI device 15 The method of claim 14 simulation of contents of PCI configuration space including populating at least one base
4. PCI configuration space associated with the simulated PCI device e g simulation of contents of PCI configuration space can include populating at least one base register with an address associated with the claimed memory At 540 at least some of the claimed memory is employed as simulated memory mapped I O registers of the simulated PCI device Next at 550 a device driver associated with the simulated PCI device e g device driver associated with simulated PCI device 420 is loaded At 560 a thread that monitors the simulated memory mapped I O registers for a change in order to simulate behavior of the simulated PCI device is instantiated e g a memory mapped I O space simulator 130 At 570 a thread that changes at least one of the simulated memory mapped I O registers in order to simulate behavior of the simulated PCI device is instantiated e g a memory mapped I O space simulator 130 Turning to FIG 6 a method for a PCI device simulation 600 in accordance with an aspect of the present invention is illustrated At 610 a device driver associated with the simulated PCI device e g device driver associated with simulated PCI device 420 is loaded At 620 a thread that monitors the simulated memory mapped I O registers for a change in order to simulate behavior of the simulated PCI device is instantiated e g a memory mapped I O space simulator 130 At 630 a thread that changes at least one of 0 20 25 40 4
5. register with an address associated with the claimed memory 16 The method of claim 12 claiming an amount of memory including reducing an amount of memory available to the operating system 17 The method of claim 12 identification of at least some ofthe claimed memory as residing on a PCI bus being based upon a filter driver that modifies a resource requirement reported by a root PCI bus hierarchy to include at least some of the claimed memory 18 The method of claim 12 identification of at least some ofthe claimed memory as resident on a PCI bus being based upon modification of a BIOS description of memory 19 A PCI simulation component comprising computer implemented means for simulating behavior of a simulated PCI device computer implemented means for claiming an amount of memory computer implemented means for identifying at least some of the claimed memory as residing on a PCI bus and computer implemented means for identifying the simu lated PCI device to an operating system wherein identification of at least some of the claimed memory as residing on a PCI bus being based upon modification of an ACPI BIOS Differentiated System Description Table in order to represent at least some of the claimed memory as being part of a root of a PCI bus hierarchy
6. some and or substantially all of the activity of an actual PCI device It is to be appreciated that the system 400 the operating system 410 the device driver associated with a simulated PCI device 420 the PCI driver 430 and or the Plug and Play manager 440 can be computer components as that term is defined herein Turning briefly to FIGS 5 and 6 methodologies that may beimplemented in accordance with the present invention are illustrated While for purposes of simplicity of explanation the methodologies are shown and described as a series of US 7 155 379 B2 9 blocks it is to be understood and appreciated that the present invention is not limited by the order of the blocks as some blocks may in accordance with the present invention occur in different orders and or concurrently with other blocks from that shown and described herein Moreover not all illustrated blocks may be required to implement the meth odologies in accordance with the present invention The invention may be described in the general context of computer executable instructions such as program modules executed by one or more components Generally program modules include routines programs objects data structures etc that perform particular tasks or implement particular abstract data types Typically the functionality of the pro gram modules may be combined or distributed as desired in various embodiments Referring to FIG 5 a method of simulation of
7. the volatile data associated with the execution of the thread A thread s context includes the contents of system registers and the virtual address belonging to the thread s process Thus the actual data comprising a thread s context varies as it executes Referring to FIG 1 a PCI simulation component 100 in accordance with an aspect of the present invention is illus trated The PCI simulation component 100 comprises an initialization component 1106 a configuration space simula tor 120 and a memory mapped 1 0 space simulator 130 The PCI simulation component 100 facilitates simulation of PCI device s e g hardware thus reducing difficulties with traditional method s of developing software for PCI device s Conventionally it has been difficult to create software e g device driver s for new PCI device s until the actual PCI device s were available This resulted in significant period s of time during which hardware was physically available but not available for use by computer system s The PCI simulation component 100 claims an amount of memory from a computer system not shown The PCI simulation component 100 then identifies to an operating system not shown at least some of the claimed memory as residing on a PCI bus Thereafter the PCI simulation component 100 identifies the simulated PCI device to the operating system The PCI simulation component 100 fur ther simulates behavior of a simulated PCI device thus perm
8. 20 e g PCI simulation component 100 For example the initialization component 110 can provide information to the operating system s boot file causing the operating system kernel s memory manager to stop using the portion for use by the PCI simulation com ponent 220 e g add MAXMEM as an argument in a boot ini file Referring back to FIG 1 the initialization component 110 further identifies to the operating system that at least some of the claimed memory resides on a PCI bus In one example this identification can be based at least in part upon modification of an Advance Configuration and Power Interface specification ACPI Basic Input Output System BIOS Differentiated System Description Table DSDT in order to represent at least some of the claimed memory as being part of a root of a PCI bus hierarchy In another example this identification can be based at least in part upon a filter driver that modifies a resource requirement reported by a root PCI bus hierarchy to include at least some of the claimed memory In yet a third example this identi 20 25 30 35 40 45 50 55 60 65 6 fication can be based at least in part upon modification of a BIOS description of memory In yet a fourth example this identification can be based at least in part upon modifica tion ofthe memory that the operating system uses by passing arguments to a kernel of the operating system Once the i
9. 410 Identification of the simulated PCI device to the operating system can be based at least in part upon simulation of contents of PCI configuration space associated with the simulated PCI device e g by the configuration space simulator 120 The configuration space simulator 120 of the PCI simulation component 100 can hook functions in the operating system 410 that read and write configuration space Thus when a PCI driver 430 in the operating system 410 scans the PCI bus the configura tion space simulator 120 can provide data that convinces the PCI driver 430 that the simulated PCI device is present in the system Since the information stored in the configuration space for the device also contains the registers that control which part of the memory mapped I O space the device uses the configuration space simulator 120 can pre populate those virtual registers with the physical address of the memory of which it has taken control Thus simulation of contents of PCI configuration space can include populating at least one base register with an address associated with the claimed memory e g claimed memory acting as simulated memory mapped I O register s of the simulated PCI device Thereafter the PCI driver 430 can communicate to a Plug and Play manager 440 that the simulated PCI device has been added to the system The PCI driver 430 can also communicate to the Plug and Play manager 440 that the simulated PCI device is using the add
10. 5 50 55 65 10 the simulated memory mapped I O registers in order to simulate behavior of the simulated PCI device is instantiated e g a memory mapped I O space simulator 130 In order to provide additional context for various aspects ofthe present invention FIG 7 and the following discussion are intended to provide a brief general description of a suitable operating environment 710 in which various aspects of the present invention may be implemented While the invention is described in the general context of computer executable instructions such as program modules executed by one or more computers or other devices those skilled in the art will recognize that the invention can also be imple mented in combination with other program modules and or as a combination of hardware and software Generally however program modules include routines programs objects components data structures etc that perform par ticular tasks or implement particular data types The oper ating environment 710 is only one example of a suitable operating environment and is not intended to suggest any limitation as to the scope of use or functionality of the invention Other well known computer systems environ ments and or configurations that may be suitable for use with the invention include but are not limited to personal computers hand held or laptop devices multiprocessor sys tems microprocessor based systems programmable con sumer
11. 560 570 FIG 5 U S Patent Dec 26 2006 Sheet 6 of 7 START LOAD A DEVICE DRIVER ASSOCIATED WITH THE SIMULATED PCI DEVICE 5 INSTANTIATE A THREAD THAT MONITORS THE SIMULATED MEMORY MAPPED I O REGISTERS FOR A CHANGE IN ORDER TO SIMULATE BEHAVIOR OF THE SIMULATED PCI DEVICE INSTANTIATE A THREAD THAT CHANGES AT LEAST ONE OF THE SIMULATED MEMORY MAPPED I O REGISTERS IN ORDER TO SIMULATE BEHAVIOR OF THE SIMULATED PCI DEVICE US 7 155 379 B2 600 Ec 610 620 630 FIG 6 U S Patent Dec 26 2006 Sheet 7 of 7 US 7 155 379 B2 NEN cnm Operating System 710 De ES 730 i Applications 4 Output Adapter s Interface l Port s Output Device s Input Device s Network Interface Communication Connection s Disk Storage 748 Remote Computer s Memory Storage 746 FIG 7 US 7 155 379 B2 1 SIMULATION OF A PCI DEVICE S MEMORY MAPPED I O REGISTERS TECHNICAL FIELD The present invention relates generally to PCI device s and more particular to simulation of a PCI device s memory mapped I O register s BACKGROUND OF THE INVENTION The Peripheral Component Interface PCI bus is a high performance 32 bit or 64 bit bus with multiplexed address and data lines The bus is intended for use as an interconnect mechanism between highly integrated peripheral controller c
12. Search 703 13 a configuration space simulator and a memory mapped I O 703 14 20 21 23 24 17 714 25 733 space simulator The initialization component can claim M _710 22 8 amount of memory by modifying the amount of memory See application file for complete search history that an operating system has available to it The initialization 56 References Cited component further identifies to the operating system that at U S PATENT DOCUMENTS 6 026 230 A 2 2000 Lin et al 703 13 6 182 242 Bl 1 2001 Brogan et al 6 279 122 Bl 8 2001 Hitchcock et al 6 324 609 11 2001 Davis et al 6 336 152 Bl 1 2002 Richman et al 6 374 340 Bl 4 2002 Lanus et al 6 418 485 Bl 7 2002 Cooper et al 6 442 514 BI 8 2002 Le 703 21 6 484 227 Bl 11 2002 Mergard et al 6 484 281 B1 11 2002 Wang et al 714 733 6 499 074 Bl 12 2002 Mehta et al 6 629 157 B1 9 2003 Falardeau et al 710 10 420 DEVICE DRIVER least some of the claimed memory resides on a PCI bus The configuration space simulator causes the operating system to accept that the simulated PCI device is present in the system The memory mapped I O space simulator simulates device and can comprise can comprise a thread that monitors the simulated memory mapped I O registers for a change in order to simulate behavior of the simulated PCI device Additionall
13. THE INVENTION The present invention is now described with reference to the drawings wherein like reference numerals are used to refer to like elements throughout In the following descrip tion for purposes of explanation numerous specific details are set forth in order to provide a thorough understanding of the present invention It may be evident however that the present invention may be practiced without these specific details In other instances well known structures and devices are shown in block diagram form in order to facilitate describing the present invention As used in this application the term computer compo nent is intended to refer to a computer related entity either hardware a combination of hardware and software soft ware or software in execution For example a computer component may be but is not limited to being a process running on a processor a processor an object an executable a thread of execution a program and or a computer By way of illustration both an application running on a server and the server can be a computer component One or more computer components may reside within a process and or thread of execution and a component may be localized on one computer and or distributed between two or more com puters A thread is the entity within a process that the operating system kernel schedules for execution As is well known in the art each thread has an associated context which is
14. United States Patent US007155379B2 12 10 Patent No US 7 155 379 B2 Oshins et al 45 Date of Patent Dec 26 2006 54 SIMULATION OF A PCI DEVICE S 6 748 461 1 6 2004 Oshins et al 710 8 MEMORY MAPPED I O REGISTERS 6 810 442 1 10 2004 Lin etal 710 22 75 1 L Jacob Oshi Seattle WA US 6 820 219 1 11 2004 Huang et al 714 25 nventors Jacob Oshins Seattle Brandon Allsop Monroe WA US 6 980 944 B1 12 2005 Oshins et al 2003 0149962 1 8 2003 Willis et al 717 135 73 Assignee Microsoft Corporation Redmond WA US Notice Subject to any disclaimer the term of this OTHER PUBLICATIONS patent is extended or adjusted under 35 f 5 U S C 154 b by 670 days PCISIM A Simulation Tool for PCI Bus Based Systems R Sharp User s Manual Dec 1999 21 Appl No 10 374 439 ong 22 Filed Feb 25 2003 Primary Examiner Fred Ferris 74 Agent Firm Amin amp Calvi 65 Prior Publication Data cro US 2004 0236564 A1 Nov 25 2004 57 ABSTRACT 51 Int CI G06F 13 10 2006 01 GO6F 9 44 2006 01 A component system and method for simulation of a PCI 52 U S CL aceti 703 21 703 13 703 14 device s memory mapped I O register s are provided The 703 17 703 20 703 23 703 24 710 8 710 22 PCI simulation component has an initialization component 58 Field of Classification
15. a PCI device s memory mapped I O registers 500 in accordance with an aspect of the present invention is illustrated At 510 an amount of memory is claimed e g by a PCI simulation component 100 For example claiming the amount of memory can include reducing an amount of memory avail able to the operating system At 520 at least some of the claimed memory is identified as residing on a bus e g by an initialization component 110 For example identification of at least some of the claimed memory as residing on a PCI bus can be based at least in part upon modification of an ACPI BIOS Differen tiated System Description Table in order to represent at least some of the claimed memory as being part of a root of a PCI bus hierarchy In another example identification of at least some of the claimed memory as residing on a PCI bus can be based at least in part upon a filter driver that modifies a resource requirement reported by a root PCI bus hierarchy to include at least some of the claimed memory In yet another example identification of at least some of the claimed memory as resident on a PCI bus is based at least in part upon modification of a BIOS description of memory At 530 a simulated PCI device is identified to an oper ating system e g by a configuration space simulator 120 For example identification of the simulated PCI device to the operating system can be based at least in part upon simulation of contents of
16. d memory for a change in order to simulate behavior of the simulated PCI device Additionally and or alterna tively the memory mapped I O space simulator 130 can comprise a thread that changes at least one of the simulated memory mapped I O registers e g in the claimed memory in order to simulate behavior of the simulated PCI device Thus the memory mapped I O space simulator 130 can continually scan the memory looking for changes that the US 7 155 379 B2 7 device driver associated with the simulated PCI device makes to the simulated memory mapped registers e g in the claimed memory The memory mapped I O space simu lator 130 can also write change s into the memory that will be perceived by the device driver of the simulated PCI device as change s in the simulated PCI device s hardware state Using these technique s the memory mapped I O space simulator 130 can virtually create some and or sub stantially all of the activity of an actual PCI device For example the process of directing a simulated PCI device s memory mapped I O ranges toward system RAM allows the device driver for the simulated device to access that RAM as it would real device register s since both the RAM and the actual device which doesn t exist yet exist in Memory Address Space The same operating system primi tives for reading writing and or mapping that memory will work While FIG 1 is a block diagram illustrating components for the PCI simula
17. ed memory e g claimed memory acting as simulated memory mapped I O register s of the simulated PCI device For example referring briefly to FIG 3 an exemplary PCI header 300 in accordance with an aspect of the present invention is illustrated The header 300 includes a plurality of fields including Base Address Register 0 310 Base Address Register 1 310 Based Address Register 2 310 Base Address Register 3 310 Base Address Register 4 310 and Based Address Register 5 310 collectively referred to as Base Address Registers 310 One or more of the Base Address Registers 310 can include a pointer to the claimed memory Returning to FIG 1 thereafter the PCI driver can com municate to a Plug and Play manager not shown that the simulated PCI device has been added to the system The PCI driver can also communicate to the Plug and Play manager that the simulated PCI device is using the address space backed by the claimed memory This causes the Plug and Play manager to load a device driver associated with the simulated PCI device not shown Thus the PCI simulation component 100 facilitates testing development of the simu lated PCI device for example before the actual hardware PCI device is available The memory mapped I O space simulator 130 simulates behavior of a simulated PCI device The memory mapped VO space simulator 130 can comprise a thread that monitors the simulated memory mapped I O registers e g in the claime
18. electronics network PCs minicomputers mainframe computers distributed computing environments that include the above systems or devices and the like With reference to FIG 7 an exemplary environment 710 for implementing various aspects of the invention includes a computer 712 The computer 712 includes a processing unit 714 a system memory 716 and a system bus 718 The system bus 718 couples system components including but not limited to the system memory 716 to the processing unit 714 The processing unit 714 can be any of various available processors Dual microprocessors and other multiprocessor architectures also can be employed as the processing unit 714 The system bus 718 can be any of several types of bus structure s including the memory bus or memory controller a peripheral bus or external bus and or a local bus using any variety of available bus architectures including but not limited to an 8 bit bus Industrial Standard Architecture ISA Micro Channel Architecture MSA Extended ISA EISA Intelligent Drive Electronics IDE VESALocal Bus VLB Peripheral Component Interconnect PCI Uni versal Serial Bus USB Advanced Graphics Port AGP Personal Computer Memory Card International Association bus PCMCIA and Small Computer Systems Interface SCSD The system memory 716 includes volatile memory 720 and nonvolatile memory 722 The basic input output system BIOS containing the basic routines to transfer inf
19. ice driver s associated with the PCI device In accordance with an aspect of the present invention the PCI simulation component simulates aspect s of a simu lated PCI device for example those which are visible to software in the memory mapped I O space The PCI simu lation component further simulates the configuration space for the simulated PCI device The initialization component performs initialization for the PCI simulation component The initialization component claims an amount of memory from a computer system The initialization component can accomplish this by modifying the amount of memory that the operating system has avail able to it By claiming some of the memory for itself the initialization component can then operate on that memory without colliding with the operating system This can be necessary for example since the operating system generally attempts to enforce a separation between address space used by device s e g PCI device s and that used by main memory In one example the initialization component claims an amount of memory by reducing an amount of memory available to the operating system At least some of the claimed memory is then utilized by the configuration space simulator and or the memory mapped I O space simulator For example the initialization component can provide infor mation to the operating system s boot file causing the operating system kernel s memory manager to stop using the portion f
20. ies the simu lated PCI device to the operating system Identification of the simulated PCI device to the operating system can be based at least in part upon simulation of contents of PCI configuration space associated with the simulated PCI device The configuration space simulator can hook functions in the operating system that read and write configuration space Thus when a PCI driver in the operating system scans the PCI bus the configuration space simulator can provide data that convinces the PCI driver that the simulated PCI device is present in the system Since the information stored in the US 7 155 379 B2 3 configuration space for the PCI device also contains regis ters that control which part of the memory mapped I O space the device uses the configuration space simulator can pre populate those virtual registers with the physical address of the claimed memory of which it has taken control Thus simulation of contents of PCI configuration space can include populating at least one base register with an address associated with the claimed memory e g claimed memory acting as simulated memory mapped I O register s of the simulated PCI device Thereafter the PCI driver can communicate to a Plug and Play manager that the simulated PCI device has been added to the system The PCI driver can also communicate to the Plug and Play manager that the simulated PCI device is using the address space that claimed memory This cause
21. itting development and or testing of a device driver not shown associated with the simulated PCI device not shown The present invention can thus significantly reduce the amount of time during which a PCI device is available without software support e g device driver s associated with the PCI device US 7 155 379 B2 5 PCI device s typically implement three address spaces I O memory mapped 1 0 and configuration 1 space can correspond for example to an I O space of an Intel brand processor Configuration space is used generally for set ting up the PCI device Memory mapped I O space can involve a PCI device which has control register s in address space traditionally addressed as memory While the control register s are addressed as memory the value s written and read from a particular control register can be different as distinguished from memory e g RAM which generally returns the same value that was last written For example for a complicated device such as a USB controller the control register s don t just store previously written values a bit can have meaning e g one bit can indicate that a USB port is active while another bit can enable the port In accordance with an aspect of the present invention the PCI simulation component 100 simulates aspect s of a simulated PCI device for example those which are visible to software in the memory mapped I O space The PCI simulation compone
22. nds certain illustrative aspects of the invention are described herein in connection with the following description and the annexed drawings These aspects are indicative however of but a few of the various ways in which the principles of the invention may be employed and the present invention is intended to include all such aspects and their equivalents Other advantages and novel features of the invention may become apparent from the following detailed description of the invention when considered in conjunction with the drawings BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 is a block diagram of a PCI simulation component in accordance with an aspect of the present invention FIG 2 is a block diagram of an exemplary memory in accordance with an aspect of the present invention FIG 3 is a block diagram of an exemplary PCI header in accordance with an aspect of the present invention FIG 4 is a block diagram of a PCI simulation system in accordance with an aspect of the present invention FIG 5 is a flow chart of a method of simulation of a PCI device s memory mapped I O registers in accordance with an aspect of the present invention 20 25 30 35 40 45 50 55 60 65 4 FIG 6 is a flow chart of a method for a PCI device simulation in accordance with an aspect of the present invention FIG 7 illustrates an example operating environment in which the present invention may function DETAILED DESCRIPTION OF
23. nitialization component 110 has taken control of at least some of the claimed memory and caused the operating system to accept that it resides on a PCI bus then the configuration space simulator 120 can cause the oper ating system to accept that the simulated PCI device is present in the system e g the configuration space simulator 120 identifies the simulated PCI device to the operating system Identification of the simulated PCI device to the operating system can be based at least in part upon simu lation of contents of PCI configuration space associated with the simulated PCI device e g by the configuration space simulator 130 The configuration space simulator 120 can hook functions in the operating system that read and write configuration space Thus when a PCI driver not shown in the operating system scans the PCI bus the configuration space simulator 120 can provide data that convinces the PCI driver that the simulated PCI device is present in the system Since the information stored in the configuration space for the PCI device also contains registers that control which part of the memory mapped I O space the device uses the configura tion space simulator 120 can pre populate those virtual registers with the physical address of the claimed memory of which it has taken control Thus simulation of contents of PCI configuration space can include populating at least one base register with an address associated with the claim
24. nt 100 further simulates the configura tion space for the simulated PCI device Thus the PCI simulation component 100 of the present invention can employ memory and software to simulate the behavior of a PCI device s memory mapped register s The initialization component 110 performs initialization for the PCI simulation component 100 The initialization component 110 claims an amount of memory from a com puter system not shown For example the initialization component 100 can accomplish this by modifying the amount of memory that the operating system has available to it By claiming some of the memory for itself the initialization component can then operate on that memory without colliding with the operating system This can be necessary for example since the operating system generally attempts to enforce a separation between address space used by device s e g PCI device s and that used by main memory In one example the initialization component 110 claims an amount of memory by reducing an amount of memory available to the operating system At least some of the claimed memory is then utilized by the configuration space simulator 120 and or the memory mapped I O space simu lator 130 Referring briefly to FIG 2 an exemplary memory 200 in accordance with an aspect of the present invention is illustrated The memory 200 comprises a portion for use by the operating system 210 and a portion for use by the PCI simulation component 2
25. ogies include Fiber Distrib uted Data Interface FDDI Copper Distributed Data Inter 20 25 30 35 40 45 50 55 60 65 12 face CDDI Ethernet IEEE 802 3 Token Ring IEEE 802 5 and the like WAN technologies include but are not limited to point to point links circuit switching networks like Inte grated Services Digital Networks ISDN and variations thereon packet switching networks and Digital Subscriber Lines DSL Communication connection s 750 refers to the hardware software employed to connect the network interface 748 to the bus 718 While communication connection 750 is shown for illustrative clarity inside computer 712 it can also be external to computer 712 The hardware software necessary for connection to the network interface 748 includes for exemplary purposes only internal and external technologies such as modems including regular telephone grade modems cable modems and DSL modems ISDN adapters and Ethernet cards What has been described above includes examples of the present invention It is of course not possible to describe every conceivable combination of components or method ologies for purposes of describing the present invention but one of ordinary skill in the art may recognize that many further combinations and permutations of the present inven tion are possible Accordingly the present invention is intended to embrace all such alterations modifications and variations
26. omponents peripheral add in cards and processor memory systems PCI is a widely accepted and implemented expan sion standard Hardware vendors of PCI device s have pressure from the computer marketplace to have software in place as PCI device s become available This has traditionally lead to limited time and or ability to debug software for the PCI device s Additional problem s can occur when the PCI device s require infrastructure from operating system s The introduction of Personal Computer Memory Card Inter national Association PCMCIA standard for cards inserted into the side of laptop computers Universal Serial Bus USB standard and Bluetooth standard for wireless com munication are examples of situations in which hardware device s were introduced with little or no operating system infrastructure facilitating interconnection SUMMARY OF THE INVENTION The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention This summary is not an extensive overview of the invention It is not intended to identify key critical elements of the invention or to delineate the scope of the invention Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later The present invention provides for a PCI simulation component comprising an initialization component a con figura
27. or example a USB port may be used to provide input to computer 712 and to output information from computer 712 to an output device 740 Output adapter 742 is provided to illustrate that there are some output devices 740 like monitors speakers and print ers among other output devices 740 that require special adapters The output adapters 742 include by way of illus tration and not limitation video and sound cards that provide a means of connection between the output device 740 and the system bus 718 It should be noted that other devices and or systems of devices provide both input and output capabilities such as remote computer s 744 Computer 712 can operate in a networked environment using logical connections to one or more remote computers such as remote computer s 744 The remote computer s 744 can be a personal computer a server a router a network PC a workstation a microprocessor based appliance a peer device or other common network node and the like and typically includes many or all of the elements described relative to computer 712 For purposes of brevity only a memory storage device 746 is illustrated with remote com puter s 744 Remote computer s 744 is logically connected to computer 712 through a network interface 748 and then physically connected via communication connection 750 Network interface 748 encompasses communication net works such as local area networks LAN and wide area networks WAN LAN technol
28. or of the simulated PCI device 9 The PCI simulation component of claim 7 the memory mapped I O space simulator further comprising a thread that changes at least one of the simulated memory mapped I O registers in order to simulate behavior of the simulated PCI device 10 A PCI simulation system comprising an operating system and memory that executes and holds the following computer components a PCI simulation component comprising a memory mapped I O space simulator that simulates behavior of a simulated PCI device an initialization component that claims an amount of the memory and identifies at least some of the claimed memory as residing on a PCI bus and a configuration space simulator that identifies the simulated PCI device to the operating system wherein the initialization component claims an amount of memory by reducing an amount of memory available to the operating system at least one of the configuration space simulator and the memory mapped I O space simulator utilizing at least some of the claimed memory and wherein identification of at least some of the claimed memory as residing on a PCI bus being based upon a filter driver that modifies a resource requirement reported by a root PCI bus hierarchy to include at least some of the claimed memory 11 The system of claim 10 further comprising a device driver associated with the simulated PCI device 12 A method of simulation of a PCI device s memory mapped I
29. or use by the PCI simulation component e g add MAXMEM as an argument in a boot ini file The initialization component further identifies to the operating system that at least some of the claimed memory resides on a PCI bus In one example this identification can be based at least in part upon modification of an Advance Configuration and Power Interface specification ACPI Basic Input Output System BIOS Differentiated System Description Table DSDT in order to represent at least some of the claimed memory as being part of a root of a PCI bus hierarchy In another example this identification can be based at least in part upon a filter driver that modifies a resource requirement reported by a root PCI bus hierarchy to include at least some of the claimed memory In yet a third example this identification can be based at least in part upon modification of a BIOS description of memory In yet a fourth example this identification can be based at least in part upon modification of the memory that the operating system uses by passing arguments to a kernel of the oper ating system Once the initialization component has taken control of at least some of the claimed memory and caused the operating system to accept that it resides on a PCI bus the configu ration space simulator then causes the operating system to accept that the simulated PCI device is present in the system e g the configuration space simulator identif
30. ormation between elements within the computer 712 such as during start up is stored in nonvolatile memory 722 By way of illustration and not limitation nonvolatile memory 722 can include read only memory ROM programmable ROM PROM electrically programmable ROM EPROM elec trically erasable ROM EEPROM or flash memory Vola tile memory 720 includes random access memory RAM which acts as external cache memory By way of illustration and not limitation RAM is available in many forms such as synchronous RAM SRAM dynamic RAM DRAM syn chronous DRAM SDRAM double data rate SDRAM DDR SDRAM enhanced SDRAM ESDRAM Syn chlink DRAM SLDRAM and direct Rambus RAM DRRAM US 7 155 379 B2 11 Computer 712 also includes removable nonremovable volatile nonvolatile computer storage media FIG 7 illus trates for example a disk storage 724 Disk storage 724 includes but is not limited to devices like a magnetic disk drive floppy disk drive tape drive Jaz drive Zip drive LS 100 drive flash memory card or memory stick In addition disk storage 724 can include storage media sepa rately or in combination with other storage media including but not limited to an optical disk drive such as a compact disk ROM device CD ROM CD recordable drive CD R Drive CD rewritable drive CD RW Drive or a digital versatile disk ROM drive DVD ROM To facilitate con nection of the disk storage devices 724 to the system bus
31. ress space that claimed memory This causes the Plug and Play manager 440 to load the device driver associated with the simulated PCI device 420 Thus the system 400 facilitates testing development of the simulated PCI device for example before the actual hardware PCI device is available The memory mapped I O space simulator 130 of the PCI simulation component 100 simulates behavior of a simulated PCI device The memory mapped I O space simulator 130 can comprise a thread that monitors the simulated memory mapped I O registers in the claimed memory 220 for a change in order to simulate behavior of the simulated PCI device Additionally and or alternatively the memory mapped I O space simulator 130 can comprise a thread that changes at least one of the simulated memory mapped I O registers in the claimed memory 220 in order to simulate behavior of the simulated PCI device Thus the memory mapped I O space simulator 130 continually scan the claimed memory 220 looking for changes that the device driver associated with the simulated PCI device 420 makes to the simulated memory mapped registers in the claimed memory 220 The memory mapped I O space simulator 130 can also write change s into the claimed memory 220 that will be perceived by the device driver of the simulated PCI device 420 as change s in the simulated PCI device s hardware state Using these tech nique s the memory mapped I O space simulator 130 can virtually create
32. s the Plug and Play manager to load a device driver associated with the simulated PCI device Thus the PCI simulation component facilitates testing development of the simulated PCI device for example before the actual hardware PCI device is available The memory mapped I O space simulator simulates behavior of a simulated PCI device The memory mapped I O space simulator can comprise a thread that monitors the simulated memory mapped I O registers e g in the claimed memory for a change in order to simulate behavior of the simulated PCI device Additionally and or alterna tively the memory mapped I O simulator can comprise a thread that changes at least one of the simulated memory mapped I O registers e g in the claimed memory in order to simulate behavior of the simulated PCI device Thus the memory mapped I O space simulator can con tinually scan the memory looking for changes that the device driver associated with the simulated PCI device makes to the simulated memory mapped registers e g in the claimed memory The memory mapped I O space simulator can also write change s into the memory that will be perceived by the device driver of the simulated PCI device as change s in the simulated PCI device s hardware state Using these technique s the memory mapped I O space simulator can virtually create some and or substantially all of the activity of an actual PCI device To the accomplishment of the foregoing and related e
33. simulation component 100 claims an amount of memory 200 the claimed memory 220 The PCI simulation component 100 then identifies to the operating system 410 at least some of the claimed memory 220 as residing on a PCI bus Thereafter the PCI simulation component 100 identifies the simulated PCI device to the operating system 410 The PCI simulation component 100 further simulates behavior of a simulated PCI device thus permitting development and or testing of the device driver associated with the simulated PCI device 420 The present invention can thus significantly reduce the amount of time during which a PCI device is available without software support e g device driver associated with the PCI device 420 The PCI simulation component 100 simulates aspect s of a simulated PCI device and the configuration space for the simulated PCI device Thus the PCI simulation component 100 of the present invention can employ memory and software to simulate the special behavior of a PCI device s memory mapped register s Once the PCI simulation component 100 has taken control of the claimed memory 220 and caused the operating system 410 to accept that it resides on a PCI bus then it must cause 20 25 30 35 40 45 50 55 60 65 8 the operating system 410 to accept that the simulated PCI device is present in the system e g the PCI simulation component 100 identifies the simulated PCI device to the operating system
34. that fall within the spirit and scope of the appended claims Furthermore to the extent that the term includes is used in either the detailed description or the claims such term is intended to be inclusive in a manner similar to the term comprising as comprising is inter preted when employed as a transitional word in a claim What is claimed is 1 A PCI simulation component comprising a computer processor and memory that executes and holds the following computer components a memory mapped I O space simulator that simulates behavior of a simulated PCI device an initialization component that claims an amount of memory and identifies at least some of the claimed memory as residing on a PCI bus and a configuration space simulator that identifies the simu lated PCI device to an operating system wherein the initialization component claims an amount of memory by reducing an amount of memory available to the operating system at least one of the configuration space simulator and the memory mapped I O space simulator utilizing at least some of the claimed memory and wherein identification of at least some of the claimed memory as residing on a PCI bus being based upon modification of an ACPI BIOS Differentiated System Description Table in order to represent at least some of the claimed memory as being part of a root of a PCI bus hierarchy 2 The PCI simulation component of claim 1 identifica tion of the sim
35. tion component 100 it is to be appreciated that the PCI simulation component 100 the initialization component 110 the configuration space simulator 120 and or the memory mapped I O space simulator 130 can be implemented as one or more computer components as that term is defined herein Thus it is to be appreciated that computer executable components operable to implement the PCI simulation component 100 the initialization component 110 and or the memory mapped I O space simulator 130 can be stored on computer readable media including but not limited to an ASIC application specific integrated circuit CD compact disc DVD digital video disk ROM read only memory floppy disk hard disk EEPROM electri cally erasable programmable read only memory and memory stick in accordance with the present invention Turning to FIG 4 a PCI simulation system 400 in accordance with an aspect of the present invention is illus trated The system 400 includes a PCI simulation component 100 memory 200 and an operating system 410 Optionally the system 400 can include a device driver associated with a simulated PCI device 420 The system 400 facilitates simulation of PCI device s e g hardware for example prior to availability of the actual PCI device s As discussed supra the PCI simulation component 100 comprises an initialization component 110 a configuration space simulator 120 and a memory mapped I O space simu lator 130 The PCI
36. tion space simulator and a memory mapped I O space simulator The PCI simulation component facilitates simu lation of PCI device s e g hardware thus reducing diffi culties with traditional method s of developing software for PCI device s Conventionally it has been difficult to create software e g device driver s for new PCI device s until the actual PCI device s were available This resulted in significant period s of time during which hardware was physically available but not available for use by computer system s Hardware level simulators for PCI device s exist however cost s associated with the hardware level simulators can be prohibitive The present invention can significantly reduce cost s associated with PCI device simu lation The PCI simulation component claims an amount of memory from a computer system The PCI simulation component then identifies to an operating system at least some of the claimed memory as residing on a PCI bus Thereafter the PCI simulation component identifies the simulated PCI device to the operating system The PCI simulation component further simulates behavior of a simu lated PCI device thus permitting development and or test ing of a device driver associated with the simulated PCI 10 5 30 35 40 45 65 2 device The present invention can thus significantly reduce the amount of time during which a PCI device is available without software support e g dev
37. ulated PCI device to the operating system being based upon simulation of contents of PCI configura tion space associated with the simulated PCI device 3 The PCI simulation component of claim 2 simulation of contents of PCI configuration space including populating at least one base register with an address associated with the claimed memory 4 The PCI simulation component of claim 1 identifica tion of at least some of the claimed memory as residing on a PCI bus being based upon a filter driver that modifies a resource requirement reported by a root PCI bus hierarchy to include at least some of the claimed memory US 7 155 379 B2 13 5 The PCI simulation component of claim 1 identifica tion of at least some of the claimed memory as resident on a PCI bus being based upon modification of a BIOS descrip tion of memory 6 The PCI simulation component of claim 1 identifica tion of at least some of the claimed memory as resident on a PCI bus being based upon modification of the memory that the operating system uses by passing arguments to a kernel of the operating system 7 The PCI simulation component of claim 1 at least some of the claimed memory acting as a simulated memory mapped I O register of the simulated PCI device 8 The PCI simulation component of claim 7 the memory mapped I O space simulator further comprising a thread that monitors the simulated memory mapped I O registers for a change in order to simulate behavi
38. y and or alternatively the memory mapped I O space simulator can comprise a thread that changes at least one of the simulated memory mapped I O registers in order to simulate behavior of the simulated PCI device 19 Claims 7 Drawing Sheets yo PCI SIMULATION COMPONENT INITIALIZATION A COMPONENT CONFIGURATION V L 430 440 MANAGER OPERATING SYSTEM 410 US 7 155 379 B2 Page 2 OTHER PUBLICATIONS Integrated Approach to PCI Subsystem Verification in SOC s D Duxstad EETimes 2000 PCI Device Compliance Testing Using a Mixed C Verilog Envi ronment D Duxstad et al A Design Modleing and Simulation Methodology for PCI X Subsystems M Cases et al IEEE 0 7803 6450 3 00 2000 IEEE PCI SIG PCI Local Bus Specification Revision 3 0 Aug 12 2002 1 344 PCI SIG Portland OR Yan Shoumeng et al A Simulation Framework for Device Driver Development Northwestern Polytechnical University Dec 2002 4 Pages cited by examiner U S Patent Dec 26 2006 Sheet 1 of 7 110 INITIALUZATION COMPONENT 120 CONFIGURATION SPACE SIMULATOR MEMORY MAPPED I O SPACE SIMULATOR 130 PCI SIMULATION COMPONENT 100 US 7 155 379 B2 FIG 1 U S Patent Dec 26 2006 Sheet 2 of 7 US 7 155 379 B2 200 FOR PCI SIMULATION COMPONENT USE MAXMEM MEMORY FOR OPERATING SYSTEM USE FIG 2
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