Detecting PCI devicesEarly PCsThe PC’s evolutionSlide 4Slide 5Three IA-32 address-spacesInterface to PCI Configuration SpaceReading PCI Configuration DataSlide 9Example: network interfaceVendor’s identitySlide 12Packet filtering capabilityYour NIC’s unique addressOur ‘tigon3.c demoHow we got the MAC-addressDriver’s authorsSlide 18Linux helper-functionsBig-Endian to Little-EndianIn-class exerciseSlide 22Detecting PCI devicesOn identifying the peripheral equipment installed in our PCEarly PCs •Peripheral devices in the early PCs used fixed i/o-ports and fixed memory-addresses, e.g.:–Video memory address-range: 0xA0000-0xBFFFF –Programmable timer i/o-ports: 0x40-0x43–Keyboard and mouse i/o-ports: 0x60-0x64–Real-Time Clock’s i/o-ports: 0x70-0x71–Hard Disk controller’s i/o-ports: 0x01F0-01F7–Graphics controller’s i/o-ports: 0x03C0-0x3CF–Serial-port controller’s i/o-ports: 0x03F8-0x03FF–Parallel-port controller’s i/o-ports: 0x0378-0x037AThe PC’s evolution•It became clear in the 1990s that there would be contention among equipment vendors for ‘fixed’ resource-addresses, which of course were in limited supply•Among the goals that motivated the PCI Specification was the creation of a more flexible scheme for allocating addresses that future peripheral devices could usePCI Configuration SpacePCI Configuration Space Body(48 doublewords – variable format) 64doublewordsPCI Configuration Space Header(16 doublewords – fixed format)A non-volatile parameter-storage area for each PCI device-functionPCI Configuration HeaderStatusRegisterCommandRegisterDeviceIDVendorIDBISTCacheLineSizeClass CodeClass/SubClass/ProgIFRevisionIDBase Address 0SubsystemDevice IDSubsystemVendor IDCardBus CIS PointerreservedcapabilitiespointerExpansion ROM Base AddressMinimumGrantInterruptPinreservedLatencyTimerHeaderTypeBase Address 1Base Address 2Base Address 3Base Address 4Base Address 5InterruptLineMaximumLatency 31 0 31 016 doublewordsDwords 1 - 0 3 - 2 5 - 4 7 - 6 9 - 811 - 1013 - 1215 - 14Three IA-32 address-spacesmemoryspace(4GB)i/o space(64KB)PCIconfigurationspace(16MB)accessed using a large variety of processor instructions (mov, add, or, shr, push, etc.) and virtual-to-physical address-translation accessed only by using the processor’s special ‘in’ and ‘out’ instructions (without any translation of port-addresses) i/o-ports 0x0CF8-0x0CFF dedicated to accessing PCI Configuration SpacereservedInterface to PCI Configuration SpaceCONFADD( 0x0CF8)CONFDAT( 0x0CFC)31 23 16 15 11 10 8 7 2 0ENbus(8-bits)device(5-bits)doubleword (6-bits) function(3-bits)00PCI Configuration Space Address Port (32-bits)PCI Configuration Space Data Port (32-bits)31 0 Enable Configuration Space Mapping (1=yes, 0=no)Reading PCI Configuration Data •Step one: Output the desired longword’s address (bus, device, function, and dword) with bit 31 set to 1 (to enable access) to the Configuration-Space Address-Port•Step two: Read the designated data from the Configuration-Space Data-Port:# read the PCI Header-Type field (byte 2 of dword 3) for bus=0, device=0, function=0movl $0x8000000C, %eax # setup address in EAXmovw $0x0CF8, %dx # setup port-number in DX outl %eax, %dx # output address to portmov $0x0CFC, %dx # setup port-number in DXinl %dx, %eax # input configuration longwordshr $16, %eax # shift word 2 into AL registermovb %al, header_type # store Header Type in variableDemo Program•We created a short Linux utility that searches for and reports all of your system’s PCI devices •It’s named “pciprobe.cpp” on our CS635 website•It uses some C++ macros that expand to Intel input/output instructions -- which normally are ‘privileged’ instructions that a Linux application-program is not allowed to execute (segfault!)•Our system administrator (Alex Fedosov) has created a utility (named “iopl3”) that will allow your command-shell to acquire I/O privilegesExample: network interface•We identify the network interface controller in our classroom PC’s by class-code 0x02•The subclass-code 0x00 is for ‘ethernet’•We can identify the NIC from its VENDOR and DEVICE identification-numbers:•VENDOR_ID = 0x14E4•DEVICE_ID = 0x1677•You can use the ‘grep’ command to search for these numbers in this header-file:</usr/src/linux/include/linux/pci_ids.h>Vendor’s identity•The VENDOR-ID 0x14E4 belongs to the Broadcom Corporation (headquarters in Irvine, California)•Information about this firm may be learned from the corporation’s website:<http://www.broadcom.com>•The DEVICE-ID 0x1677 is used to signify Broadcom’s BCM5751 ethernet productnicTypical NIC TX FIFORX FIFOtransceiver LANcableBUSmain memorypacketbufferCPUPacket filtering capability •Network Interface’s hardware needs to implement ‘filtering’ of network packets•Otherwise the PC’s memory-usage and processor-time will be wasted handling packets not meant for this PC to receive network packet’s layoutDestination-address (6-bytes) Source-address (6-bytes)Each data-packet begins with the 6-byte device-address of the network interface which is intended to receive itYour NIC’s unique address•You can see the Hardware Address of the ethernet controller on your PC by typing: $ /sbin/ifconfig •Look for it in the first line of screen-output that is labeled ‘eth0’, for example:•(The NIC’s filter-register stores this value)eth0 Link encap: Ethernet HWaddr 00:11:43:C9:50:3AOur ‘tigon3.c demo•We wrote a kernel module that lets users see certain register-values which pertain to the BCM5751 network interface in your classroom workstation:–(1) the PCI Configuration Space registers–(2) the Media Access Controller’s address •It also shows your machine’s node-name (in case you want to save the information)How we got the MAC-address•We do not have Broadcom’s programming datasheet -- but we do have Linux source code for the ‘tigon3’ device-driver, which includes a header-file ‘tg3.h’ found here: </usr/src/linux/drivers/net/> •If you scroll through the #define directives you will see the offset where the hardware address is stored in the memory-mapped register-space of the ‘tigon3’ interfaceDriver’s authors•The Linux kernel’s open-source driver for the Broadcom ‘tigon3’ network controller was