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TLP Packet Format: FIG: TLP Packet Format. The Transaction Layer Packet Format is defined as: Starts with a Prefix, which is an optional one and, TLP Header and then, With/Without Data Payload, At the end of TLP Packet a TLP Digest, The information in TLP Packet Format is distributed as: TLP Prefixes. Header (mandatory). Data (included when applicable): depends on the transaction type. TLP Digest (optional). FIG: TLP Byte Information TLP Header: Provides Format of the packet. Type of the packet. Length of associated data, if available. Transaction Descriptor. Address/Routing information Byte enables Message encoding Completion Status FIG: Common TLP Header. 32-bit if information. Provides: Format, TLP Packet Type, Traffic Class info, Attributes, T Heads (Presence of TLP Prefix, if present), TLP Digest, End Point (TLP is Normal or Poisoned), Address Translation (When memory is available). Length (Data Length notation denoted in 32bit words) F

PCI Configuration Space Registers (Type 0 / Type 1)

PCI Configuration Space Type 0 is for PCI devices and, for Endpoints in case of PCIe. Type 1 Config Space is for PCI host controller and, for PCI Root Complex in case of PCIe. Type 0/1 Configuration Space: FIG: Config Space. The Config Space registers are common for both type 0/1. Device ID and Vendor ID: Identify the particular device. Status register: Provides error information, updated information, etc. Command register: Controls Bus Master and different utilities. Class code: Provides category of the device (Host Controller, IDE Bridge, SATA Controller, Ethernet Controller, etc). Revision ID of PCI. BIST - Built-In Self Test. Header Type Specific area is defined by Header type (0 or 1). Cache Line Size. Table: Configuration Space Registers. Table: Command Register Table: Status Register FIG: Type 0 Configuration Space Table: TYPE 0 Registers FIG: PCIe TYPE 1 Configuration Space Table: TYPE 1 Configuration Space Registers

PCIe - Terminology, Throughput, Root Complex, End Point and, Switch

In my previous post, I introduced the topology and architecture of PCIe. After a careful study, I have gathered a detailed understanding of its terminology and working. Let's have a look! FIG: Various PCIe slots on a motherboard- PCIe x 4; 16; 1; 16; Conventional 5V 32Bit PCI, respectively. Source: Wikipedia Terminology: FIG: PCIe link between two devices consisting of one or more lane. Source: Wikipedia Switch, n-point, root complex can be directly connected with the PCIe Link. Link contains high-speed serial standard bus, which has a differential signaling. Diffrential signaling are software interrupts sent to a program to indicate an important event like user requests or illegal memory access errors (One transmit pin having two pairs of wires: Transmit +ve and -ve which increases noise immunity). *You can use kill -l on your linux/unix system to view the supported signals. For example: If +ve is affected with noise, and in a similar manner if -ve also gets

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