note3

Chapter 3 Configuring Hardware

-All OS run on hardware
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Configuring Firmware

-Well known firmware ,BIOS(Basic IN/OUT System)
-new frimware EFI/UEFI(Unified extensible Firmware interface)

-Firmware reside in EEPROM(electronically Erasable programable Read Only Memory)

firmware work flow
-->Turn on--> POST -->load bootloader --> past control to boot loader.

IRQ(Interrupt Request) = Signal send to the CPU instructing it to suspend its current activity and to handle some external event.

-in x86_64 IRQ is from 0 to 15
-modern PC provide more!
-Some IRQ already reserverd for specific purpose

0 - System Timer
1 - Keyboard
2 - Cascade for IRQs 8-15
3 - Second RS-232 serial port
4 - First RS-232 serial port
5 - Sound card or second parallel port 
6 - Floppy disk controller
7 - First parallel port
8 - Real time clock 
9 - ACPI system control interrupt (used by intel chipset for Power Management)
10 - Open intterupt
11 - Open intterupt
12 - PS/2 mouse
13 - Math coprocessor (Reserved for internal use)
14 - Primary ATA controller (/dev/hda /dev/hdb)
15 - Secondary ATA controller(/dev/hdc /dev/hdd)
* new system for Serial ATA (/dev/sda /dev/sdb)

cat /proc/interrupts = to see list of interrupts

I/O Addresses(I/O ports) = unique locations in memory that are reserved for communications between CPU and specific physical hardware(like IRQ ,cannot be shared)

cat /proc/ioports

DMA(direct memory addressing) -Hardware directly access memory without CPU

cat /proc/dma


Coldplug and hotplug

coldplug = system need to be off for plug in
hotplug = system can be on for plug in

Some tools to help user to access information and edit hardware.

1.Sysfs = mounted at /sys ,exports information about devices so that user-space can access
2. HAL-Daemon = Hardware Abstaraction Layer (hald) ,run as daemon, provides other user-space programs with information about available hardware.
3. D-Bus = Desktop Bus , run in daemon, enable proccess to commucincate with hardware, such as USB
4. /udev = mounted at /deb which creates dynamic device files as drivers are loaded and unloaded. can configure udev in /etc/udev

Configuring Expansion Cards

lspci = displays all of the information about the PCI busses in system.
-v = increase verbosity
-n = display information in numeric codes rather than translating the codes to manufacturer and device names.
-nn Displays both the manufacturer and device names and their associated numeric codes.
-s = show specific pci


Kernel Modules

-handle hardware in linux
-stored in /etc/modules
-some modules already compiled into kernel

lsmod = show modules that currently loaded into the system

Loading Kernel modules

insmod / modprobe

insmod = insert module into the kernel
	 need to load dependencies

modprobe = automatically loads any depended-on modules

insmod
exp 
insmod /lib/modules/3.16.6/kernel/drivers/bluetooth/bluetooth.ko
-require full name module
-sometimes need module options, need to refer to the documentation


modprobe 
exp 
modprobe bluetooth

-v = verbose
-C = use configuration file in /etc/modprobe.conf
-n/--dry-run = causes modprobe to perform checls and all other opertaions except module insertion.
-r = remove module
-f = froce the module loading even if the kernel version doesn't match what the module expect.
--show-dependencies = show dependecies for the module
-l = list option available form the wildcards

Removing Kernel Module

rmmod = removing module

rmmod bluetooth
-v = verbose
-f = force removal
-w = wait for the module in unused condititon before removing it

Configuring USB devices

-There are several USB controllert available 
-UHCI,OHCI,EHCI,R8A66597
-UHCI and OHCI = USB 1.0

two tools for managing USB devices:usbmgr and hotplug

usbmgr = detect usb and load module to the kernel
-but hotplug is famous

hotplug = relies on kernel support , uses files stored in/etc/hotplugto control specific USB,

COnfiguring Hard Disk

-Three Common hardisk interface
 Parallel Advanced Technology Attachment(PATA),ATA
 Serial Advanced Technology Attachment(SATA)
 Small Computer System Interface (SCSI)

++USB,IEE1394

PATA
-parallel interface,several bits is stransferred over the cable at once.
-cable are wide 
-supporting to 40 to 80 lines
-can connect up to two devices to each PATA connector,
-must be configured as MASTER and SLAVE(done via jumper)
-modern PATA support cable select
-/dev/hda /dev/hdb
-hda for master and hdb for slave
-partition hda1,hda2
-modern distibution treat PATA disks as SCSI

SATA
-FASTER than PATA
-cable much thinner

Configuring SCSI
-better than PATA
-few people use SCSI
-SCSI support 8-16
-sometimes SCSI adapter have their own firmware
-numbering is depend on SCSI ID
-lowest to highest

Design Hard Disk Layout
-create partition and format!
-Why partiton
--Multiple OS support
--Filesystem choice
--Disk Space management
--Disk Error protection
--Security
--Backup


Partitioning Systems
-Usually MBR
---data stored in the first sector of the disks
---size is very limited (2tebibytes)=2^40 bytes=512Byte
-the successor is GUID Partition Table


MBR partition
x64 system only allowed 4 partition
-but hard disk become bigger and make this new partition scheme
-PRimary
 -same as the original partition
-Extended
 -special type of primary partition that serve as placeholder for the next type
-Logical
 -reside within an extended partition

primary partition = 1-->4
logical partition = 5-->up
gap cannot exist in logical partition

MBR HOLD partition table and boot loader
-very sensitive and important
-have type code
--0x0c = FAT,0x05= old type extended partition 0x07 = NTFS ,0x82 = Linux swap, 0x83 = filesystem

GPT 
part of intel EFI spec
-can be use in PC that doesnt use EFI
-preferred in partitioning system on disks bigger than 2Tib
-employs protective MBR
-make utilities unaware of GPT
-additional data structures define GPT
-this data sturctures lies in start of disk and end of disk

--CAN create up to 128 partitions(may be raise if necessary)
--gap can occur in partition number 
-drawbacks is support for it is immature

Alternative to PARTITION
-LVM(logical volume management)
-use pvreate,vgcreate,lvcreate,lvscan to manage physical volumes(partition)
-combine partition into one big volume group
-assign them into /dev/mapper
-filsesystem size can be change!!

Mount Points
-After partition is created, it must be mount before use


Creating Partitions and Filesystems

MBR partitioning tools!

fdisk = fixed disk,to create partition for MBR

exp fdisk /dev/hda

p = display current partition = fdisk -l /dev/hda
n = create new partition
w = write table to disk and exit
q = quit without saving

After partition is created , it needs to be formatted!
-involve in low level data structures in disk


Linux Supported FileSystem
1. Ext2fs(Second Extended File System)
- tradiotanl Linux-native fs
-created for linux. and dominant 
-good choice for small /boot partition.
-non journal fs
-ext2

2. Ext3fs 
-basically ext2fs with journaling
-recover from crash quickly

3. Ext4fs 
-abily to work with very large disks

4. ReiserFS
- designed from scratch as journaling FS for Linux
-good at hadling large numbers of small files
-because sue tricks to squeeze the ends of files into each other's unused spaces
-reiserfs

5. Jfs 
- IBM developed JFS
-techincally sophisticated journaling system
-good if familiar wih AIX or OS/2 
-jfs

6. XFS
SGI created XFS for IRIX OS
-gain reputation for robustness,speed and flexibility on IRIX

7. Btrfs
-fast performer and can handle large disk and files
-maybe a successor for current fs

Different FS for Linux

1. FAT(File Allocation Table)
-old and primitive 
-the only fs supported by DOS during early day of Windows,
-all majos OS support FAT
-vary in the size of FAT(12-, 16-, 32-bit pointers)
-support long filenames
-msdos

2. NTFS(New Technology FS)
- preferred fs for Windows NT and beyond.
-linux can reand and overwrite existing files, but cannot write new files

3. HFS and HFS +
-Hierarchical FS
-for MAc OS
-Linux provides full read/write HFS 

4. ISO9660
-standard fs for CD-ROM
-come with several level
-Level 1 - similar to the original FAT
-Level 2 and 3 - add support for longer 32-character filenames
-Linux also support Rock Ridge extension for longer filenames,permissions,symbolic links, and so on.
-same with Juliet for Windows
-Windows support for both of them

5. UDF (Universal Disc Format)
-next generation fs
-use in DVD-ROM


PS = to create ISO-9660 and other optical disc fs 
- mkisofs = creates ISO-9660
-cdrecord = to writes this image to a blank CD-R
-growisofs = combine both but only works onn recordable DVD media

Creating FS

mkfs.fstype = create fs for the partition
fstype = fs type code

or mkfs -t <fs type code>

*for ext2 n ext3 mke2fs is used instead

-c = bad block Check(sign that the disk doesn't have long to live)
-m = percent, sets the reserved-space percentage

other mkfs
mkdosfs = create FAT fs
mkfs,msdks
mkfs.vfat

-F = set fat-size

Creating Swap Space
-Linux use swap partition
-extension of memory
-MBR code 0x82 
-need to defined in /etc/fstab 

mkswap = to create swap fs
exp 
mkswap /dev/sda7

swapon /dev/sda7 = use the swap space
to activate it permanenly need to change /etc/fstab

Maintaining FS

-basically tools use to maintain FS need to be used when the fs is unmounted

3 basic tools
1.dumpe2fs
2.tune2fs
3.debugfs

dumpe2fs = show information about ext2 and ext3

-h = utility will omit information about group descriptors
-can be run while the fs is mounted

xfs provide same utilites = xfs_info

Tune FS

tune2fs = change fs parameters that are reported by dumpe2fs
-c = maximum number of time the disk may be mounted without a check 
-C = set mount counter
-i = set interval for check
-j = add journal to the fs, convert ext2 to ext3
-m = set reserved block

xfs_admin = for xfs
-PLEASE USE IN UNMOUNTED FS
-l/-u = to obtain fs UUID

blkid = can display the label and UUID of any partitions

-L/-U = change the label(12 char only) and UUID (use generate to create UUID/dont set UUID that been used by other partitions)


Interactive Debugging FS

debugfs = use interactive options to debug fs

-show_super_stats/stats = same as dumpe2fs
-stat filename = display inode of the file
-undelete inode name = undelte file 
	- need to know the file inode using lsdel/list_deleted_inodes
-write internal-fiels external-file = extract file from badly damged file
-cd ,mv,cp etc
-list_requests ,lr,help ? = show help
-quit	

Checking FileSystem

fsck = checkin FS

-A = check all files in /etc/fstab
-V = verbose 
-N = will display what its normally do without doing it
-t = set fs type
-- = for inside options
	-f = force
	=i = interactive 
	-a/-p = perform automatic check
!!ONLY RUN FSCK IN UNMOUNTED FS or READ ONLY FS

Monitorin DISK use by Partition

df = summary fo disk space used 
-a = all fs
-h = human readable
-i /--inodes = show inodes
-l = local only
-T = show filesystem type
-t =limit the filesystem type to show

exp 
df /home = can be used to see disk usage of /home

MOnitoring DISK use by Directory

du = show disk usage by Directory/similar to du
-a = show disk usage for individual files as well
-c = compute grand total
-h = human readable
-l = count hard links
--max-depth = limit the report to n levels
-s = summarize
-x = limit filesystem 

MOunting and Unmounting

mount= mounting file system

-a = mount all fs in /etc/fstab

-r = mount it to read only
-v = show ver bose
-w = mount it to read write
-t = mount with file type
-L/-U = mount by label or UUID
-o = add filesystem specific options

--file that mounted is saved in /etc/mtab, this file in /etc but cannot be configure

mount options

loop = loopback fS
auto or noauto = mount or doest mount the fs at boot
user or nouser = allows or disallows ordinary users to mount the fs,Used in /etc/fstab
users = any user may unmount the fs
owner - similar to user but user must own the device
remount = change one or more mount options without explicitly unmounting a partition
ro = specifies a read-only mount of fs
rw = specifies a read write
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umount = unmount fs

basicallyy same options with mount

Permanently Mount FS

EDIT /etc/fstab

DEVICE 	MOUNTPOINT  FILESYSTEM OPTIONS DUMP FSCK
-DEVICE usually use label /UUID