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A Smart Port Card Tutorial --- Hardware John DeHart Washington University jdd@arl.wustl

A Smart Port Card Tutorial --- Hardware John DeHart Washington University jdd@arl.wustl.edu http://www.arl.wustl.edu/~jdd. References: New Links from Kits References Page. Intel Embedded Module: Data Sheet Design Guide 430HX Chipset NorthBridge SouthBridge System FPGA Memory

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A Smart Port Card Tutorial --- Hardware John DeHart Washington University jdd@arl.wustl

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  1. A Smart Port Card Tutorial --- Hardware John DeHart Washington University jdd@arl.wustl.edu http://www.arl.wustl.edu/~jdd

  2. References: New Links from Kits References Page • Intel Embedded Module: • Data Sheet • Design Guide • 430HX Chipset • NorthBridge • SouthBridge • System FPGA • Memory • Mobile Pentium with MMX • Software Developer Manuals 1,2,3 • Datasheet • APIC • Cache

  3. Motivation • Active Networking • Network Probe • High performance router architectures • PC as router is VERY limited • (Gigabit/s + Processing) on each port • MSR: Multi-Service multiport Router

  4. The Smart Port Card • Hardware: • SPC as a PC • How do they each boot? • SPC Hardware Components • What roles do they play?

  5. Typical Pentium PC CPU/Memory Bus Addr/Data Ctrl Ctrl Cache CPU North- Bridge DRAM Addr/Data/Ctrl PCI Bus Intr NMI INIT SouthBridge (PIIX3) (PIC, PIT, …) PCI Devices ISA Bus ISA Devices Super-IO BIOS BIOS RTC Uarts Kbd/Mse Floppy Parallel ...

  6. How NetBSD Boots on a PC Components: • Pentium • Boot ROM (replaced by BIOS in modern systems?) • BIOS • Bootloader • Kernel

  7. Sketch of How a PC Boots … at least what I understand… • Pentium after Reset: • fetches its first instruction from location 0xFFFFFFF0 • Boot Code must be located at 0xFFFFFFF0 • Boot Code jumps to BIOS located in ROM • Boot Code may actually be part of the BIOS... • BIOS copies itself into memory (Shadow) • BIOS remaps memory • future accesses to BIOS addresses go to memory instead of ROM. • BIOS performs system configuration (some proprietary) • Motherboard Details • Pentium Details • NB/SB Chipset Details • Device configuration: IRQs, Memory maps, ...

  8. How a PC Boots (continued…) • BIOS loads bootloader into memory (from disk…) • BIOS jumps to bootloader • Bootloader performs some more configuration: • Pentium control registers • Cache configuration • Memory/Page model • Bootloader determines what to run next. • Bootloader may have to do some device configuration. • e.g. to get OS from a disk. • Bootloader loads OS kernel into memory • Bootloader jumps to start of OS kernel

  9. How a PC Boots (continued…) • Kernel does some OS-specific configuration: • for NetBSD look in: sys/arch/i386/i386/locore.s • Determines what CPU it has (“cpuid” instruction) • Paging • Virtual Memory

  10. Typical Pentium PC (Again…) CPU/Memory Bus Addr/Data Ctrl Ctrl Cache CPU North- Bridge DRAM Addr/Data/Ctrl PCI Bus Intr NMI INIT SouthBridge (PIIX3) (PIC, PIT, …) PCI Devices ISA Bus ISA Devices Super-IO BIOS BIOS RTC Uarts Kbd/Mse Floppy Parallel ...

  11. Addr/Data Ctrl Ctrl Cache CPU North- Bridge DRAM Addr/Data/Ctrl PCI Bus Intr NMI INIT SouthBridge (PIC, PIT, …) APIC BIOS BIOS RTC Uarts What SPC Needs CPU/Memory Bus

  12. Intel Embedded Module UART1 UART2 System FPGA SPC Architecture Addr/Data Ctrl Ctrl Cache CPU North- Bridge DRAM Addr/Data/Ctrl PCI Bus NMI INIT Intr APIC RTC’ PIC PIT UART1 Interface BIOS ROM Link Interface UART2 Interface Switch Interface

  13. SPC Photo Tour Switch Interface DRAM Link Interface CPU Module APIC PCI Bus System FPGA Serial Ports

  14. SPC Components • APIC • PCI Bus Master • Pentium Embedded Module • 166 MHz MMX Pentium Processor • L1 Cache: 16KB Data, 16KB Code • L2 cache: 512 KB • NorthBridge - 33 MHz, 32 bit PCI Bus • PCI Bus Master • System FPGA • PCI Bus Slave • Xilinx XC4020XLA-1 FPGA • 20K Equivalent Gates • ~ 75% used

  15. SPC Components (continued) • Memory • EDO DRAM • 64MB (Max for current design) • SO DIMM • Switch Interface - 1 Gb Utopia • Link Interface - 1 Gb Utopia • UART • Two Serial Ports • NetBSD system console • TTY port

  16. System FPGA • Coded in VHDL • PCI slave device • Replaces some of the PIIX3 (south bridge) • Replaces some of the BIOS • Replaces some of the Super IO Chip • Provides reset capability

  17. System FPGA: PIIX3 Functionality • Programmable Interrupt Controller (PIC) • Four Interrupts supported and statically assigned: • PIT (IRQ 0) • APIC (IRQ 5) • COM1 (IRQ 4) • COM2 (IRQ 3) • Static fully-nested interrupt priority structure. • Specific End of Interrupt is the only EOI mode supported • Programmable Interval Timer (PIT) • generates a clock interrupt for NetBSD every ~10ms • Reset - covered in a later slide

  18. System FPGA: BIOS Functionality • Interrupt functionality replaced by static values • Simple 16 word by 32-bit “ROM” • implements loop waiting for location 0xFFE00 to change value • then jumps to boot loader code • Does NOT perform configuration of Northbridge • This will be done by the boot loader • Does NOT perform PCI configuration of APIC • This will be done by the APIC Driver

  19. System FPGA: Super IO Chip Functionality • UART Interface • Two Serial lines supported • Fixed IRQs • Real Time Clock • only the register accesses of the RTC are supported • no interrupts supported • i.e. supported only so NetBSD didn’t need to change • i.e. no alarms will be generated

  20. System FPGA: Reset • SPC needs a reset before every download: • switch reset: • causes SPC to be reset • causes all connections in switch to be lost • System FPGA reset • causes SPC to be reset • has no effect on the switch • Normal SouthBridge reset: • I/O Register: 0xCF9 • Hard Reset: assert CPURST, PCIRST#, and RSTDRV • write 0xCF9 0x02 (00000010b) • write 0xCF9 0x06 (00000110b) • Soft Reset: assert INIT • write 0xCF9 0x00 (00000000b) • write 0xCF9 0x04 (00000100b) bits

  21. System FPGA: Reset • SPC Reset: • a sequence of two writes to memory addresses • APIC Control cells can write to • memory addresses • configuration registers • NOT I/O Registers! Argh... • To mimic the reset structure of the SB we use: • 0xFFFFFFF0 • 0xFFFFFFF4 • Hard Reset (all we really care about) • write 0xFFFFFFF0 0x02 (00000010b) • write 0xFFFFFFF4 0x06 (00000110b) bits

  22. Caveats • Intel Embedded Module problem • Memory corruption caused by noise on M/A bus • Hopefully it will be fixed before we ship • We work around it with 25 MHz PCI and no HLT • This reduces the probability of noise on the bus • PCI Bus • 33 MHz vs. 25 MHz • NetBSD Kernel HLT instruction • if absolutely nothing to do, NetBSD does a “HLT” • this reduces power consumption • also causes large power/current swings • We have removed the HLT instruction for the SPC • Serial Cables • RS232 is not necessarily hot-swappable • sometimes you can get away with it but not always

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