Module 02 - System Architecture

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Module 02

System Architecture

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Objectives

Objective 1: Determine and Configure Hardware Settings BIOS USB Topology USB Controllers USB Devices USB Drivers USB Hotplug Reporting Your Hardware Device Management Definitions

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Objective 1: Determine and Configure Hardware Settings

Setting up a PC for Linux (or any other operating system) requires some familiarity with the devices installed in the system and their configuration

It includes: modems, network adapters, hard drives, USB controllers, and sound cards…

BIOS

The firmware located in a PC, commonly called the BIOS, is responsible for bringing all of the system hardware to a state at which it is ready to boot an operating system

Includes: testing of memory, other devices, and locating an operating system from among several storage devices…

In addition, the BIOS provides a low-level system configuration interface. Exp: allowing the user to choose such things as boot devices and resource assignments.

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BIOS

Depending on the BIOS vendor, these will include settings for disks, on-board ports (such as serial and parallel ports), and the clock, as well as many others. Date and time: set in BIOS or in OS Disks and boot devices as CD-DVD, Floopy, Network

Boot (NIC)

Using the /proc filesystem

When adding new hardware to an existing Linux system, you may wish to verify which resources the existing devices are using. The /proc filesystem, the kernel’s status repository, contains this information.

/proc/interrupts interrupts or IRQs are signals

generated by peripherals for the cpu to know.

when the cpu receives an interrupt signal, it temporarily suspends all its activities and attends to the interrupt

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Using the /proc filesystem

/proc/dma Direct Memory Access For faster peripheral devices, generating interrupts to

talk to cpu and then gain access to RAM could slow things down.

DMA solves this problem by granting the peripheral direct access to memory areas; basically bypassing the cpu.

Using the /proc filesystem

/proc/ioports: When cpu needs to

communicate to peripheral devices, it does so by writing to IO ports or simply ports.

Each device has its own separate port that is not shared with other devices.

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USB Topology

Universal Serial Bus (USB) is a type of interface used to connect various types of peripherals, ranging from keyboards and mice to hard drives, scanners, digital cameras, and printers.

The lsusb command can be used to see how devices are physically attached to a Linux system.

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USB Controllers

There are three types of USB host controllers: Open Host Controller Interface (OHCI) Universal Host Controller Interface (UHCI) Enhanced Host Controller Interface (EHCI)

OHCI and UHCI controllers are both USB 1.1 controllers, which are capable of a maximum of 12 Mbps.

EHCI controllers are USB 2.0 controllers, which are capable of a theoretical maximum of 480 Mbps

USB 3.0 Speed: 4800MbpsA USB 2.0 device attached to a USB 1.1 hub will only be

able to run at USB 1.1 speeds.

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USB Device

There are several classes of USB devices: Human Interface Device (HID)

Input devices (mice, keyboards, etc.) Communications device

Modems Mass storage device

Disk devices, flash readers, etc. Audio

Sound devices IrDA

Infrared devices Printer

Printers and USB-to-parallel cables

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USB Drivers

USB support was added to the Linux kernel in the 2.3.x development kernel series

The Linux kernel USB drivers fall into three categories: Host controller drivers: usb-ohci.o , usb-uhci.o , usb-

ehci.o Class drivers: usb-storage.o , printer.o, and audio.o… Other device drivers

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USB Hotplug

Hotplug lets you plug in new USB devices and use them immediately.

Starting with kernel 2.4 (in January 2001), hotplugging became a standard feature of Linux.

Reporting Your Hardware

Some useful tools to report information about the hardware installed include lsmod, lsdev, and lspci. lsmod: showing what

kernel modules are currently loaded.

The output of lsmod is a series of columns identifying the module name, its size, its use number, and its status.

Reporting Your Hardware

Some useful tools to report information about the hardware installed include lsmod, lsdev, and lspci. lsdev: displays

information about your system’s hardware, such as interrupt addresses and I/O ports.

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Reporting Your Hardware

Some useful tools to report information about the hardware installed include lsmod, lsdev, and lspci. lspci: displays information about your system’s PCI buses

and your installed PCI devices

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Device Management Definitions

Hotplugging: the ability of a computer system to add or remove hardware without powering the system down.

Coldplugging: In most computer systems, CPUs and memory are

coldpluggable But it is common for high-end servers and mainframes

to feature hotplug capability of these components.