101.1 Determine and configure hardware settings

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Candidates should be able to determine and configure fundamental system hardware.

Objectives

Enable and disable integrated peripherals.
Configure systems with or without external peripherals such as keyboards.
Differentiate between the various types of mass storage devices.
Set the correct hardware ID for different devices, especially the boot device.
Know the differences between coldplug and hotplug devices.
Determine hardware resources for devices.
Tools and utilities to list various hardware information (e.g. lsusb, lspci, etc.)
Tools and utilities to manipulate USB devices
Conceptual understanding of sysfs, udev, hald, dbus
/sys
/proc
/dev
modprobe
lsmod
lspci
lsusb

Find out about the hardware

HAL

HAL is Hardware Abstraction Layer. It abstracts your hardware details from you, say any first network card will be eth0. This way Linux will see any hardware as an standard hardware and you will be able to replace the hardware easily.

dbus

A line like a bus that connects all parts of the OS to each other. dbus lets different parts of the system to communicate with each other. For example, when you install a USB into your computer, dbus lets GNOME know about it. Using dbus, hardware & software can talk with each other.

udev

Supplies the software with the events and access info of devices and can handle rules.

There are a lot of devices in /dev/ and if you plugin any device, it will have a file in /dev (say /dev/sdb2). udev lets you control what will be what in /dev. For example, you can use a rule to force your 8GB flash drive with one specific vendor to be /dev/mybackup all the time or you can tell it to copy all photos to your home directory as soon as your camera is connected.

sysfs

The /sys directory is where HAL keeps its database of everything connected to the system.

jadi@funlife:~$ ls /sys
block  bus  class  dev    devices  firmware  fs  hypervisor  kernel  module  power

All block devices are at the block and bus directory has all the connected PCI, USB, serial, .. devices. Note that here in sys we have the devices based on their technology but /dev/ is abstracted.

proc directory

This is where kernel keeps its settings and properties. This directory is created on ram and files might have write accessible.

$ ls /proc/
1      1249   1451   1565   18069  20346  2426  2765  2926  3175  3317  3537  39    468   4921  53    689   969          filesystems  misc           sysvipc            
10     13     146    157    18093  20681  2452  2766  2929  3183  3318  354   397   4694  4934  538   7     97           fs           modules        timer_list         
1039   1321   147    1572   18243  21     2456  28    2934  3187  34    3541  404   4695  4955  54    737   acpi         interrupts   mounts         timer_stats        
10899  13346  148    1576   18274  21021  2462  2841  2936  3191  3450  3550  41    47    4970  546   74    asound       iomem        mtrr           tty                
10960  13438  14817  158    1859   21139  25    2851  2945  32    3459  357   42    4720  4982  55    742   buddyinfo    ioports      net            uptime             
11     13619  149    16     18617  2129   2592  2852  2947  3202  3466  36    43    4731  4995  551   75    bus          irq          pagetypeinfo   version            
11120  13661  15     1613   18781  214    26    2862  2948  3206  3467  3683  44    4756  5     56    77    cgroups      kallsyms     partitions     version_signature  
11145  13671  150    1630   1880   215    27    2865  2952  3208  3469  3699  4484  4774  50    577   8     cmdline      kcore        sched_debug    vmallocinfo        
1159   13927  151    1633   1882   2199   2707  2866  2955  3212  3470  37    4495  4795  5008  5806  892   consoles     keys         schedstat      vmstat             
1163   14     1512   1634   19     22     2708  2884  2957  3225  3474  3710  45    48    5013  60    9     cpuinfo      key-users    scsi           zoneinfo           
1164   14045  1515   1693   19061  2219   2709  2887  2961  3236  3475  3752  4506  4811  5077  61    904   crypto       kmsg         self           
1170   14047  152    17     19068  23     2710  2891  3     324   3477  3761  4529  4821  5082  62    9061  devices      kpagecount   slabinfo       
1174   14052  153    17173  19069  23055  2711  2895  3047  3261  3517  3778  4558  484   5091  677   915   diskstats    kpageflags   softirqs       
12     1409   154    1732   19075  2354   2718  29    3093  3284  3522  38    4562  4861  51    678   923   dma          loadavg      stat           
1231   1444   155    17413  2      2390   2719  2904  31    3287  3525  3803  46    4891  52    679   939   driver       locks        swaps          
1234   1446   156    17751  20     24     2723  2908  3132  3298  3528  3823  4622  49    5202  680   940   execdomains  mdstat       sys            
1236   145    1563   18     2028   2418   2763  2911  3171  33    3533  3845  4661  4907  525   687   96    fb           meminfo      sysrq-trigger

The numbers are the process IDs! There are also other files like cpuinfo, mounts, meminfo, ...

$ cat /proc/cpuinfo 
processor    : 0
vendor_id    : GenuineIntel
cpu family    : 6
model        : 42
model name    : Intel(R) Core(TM) i5-2520M CPU @ 2.50GHz
stepping    : 7
microcode    : 0x15
cpu MHz        : 3195.312
cache size    : 3072 KB
physical id    : 0
siblings    : 4
core id        : 0
cpu cores    : 2
apicid        : 0
initial apicid    : 0
fpu        : yes
fpu_exception    : yes
cpuid level    : 13
wp        : yes
flags        : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm ida arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid
bogomips    : 4983.79
clflush size    : 64
cache_alignment    : 64
address sizes    : 36 bits physical, 48 bits virtual
power management:

processor    : 1
vendor_id    : GenuineIntel
cpu family    : 6
model        : 42
model name    : Intel(R) Core(TM) i5-2520M CPU @ 2.50GHz
stepping    : 7
microcode    : 0x15
cpu MHz        : 3010.839
cache size    : 3072 KB
physical id    : 0
siblings    : 4
core id        : 0
cpu cores    : 2
apicid        : 1
initial apicid    : 1
fpu        : yes
fpu_exception    : yes
cpuid level    : 13
wp        : yes
flags        : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm ida arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid
bogomips    : 4983.79
clflush size    : 64
cache_alignment    : 64
address sizes    : 36 bits physical, 48 bits virtual
power management:

We can also write here. Since I'm on an IBM Lenovo laptop I can turn my LED on and off by writing here:

root@funlife:/proc/acpi/ibm# echo on > light 
root@funlife:/proc/acpi/ibm# echo off > light

One more traditional example is changing the max number of open files per user:

root@funlife:/proc/sys/fs# cat file-max 
797946
root@funlife:/proc/sys/fs# echo 1000000 > file-max 
root@funlife:/proc/sys/fs# cat file-max 
1000000

Another very useful directory here, is /proc/sys/net/ipv4 which controls real time networking configurations.

All these changes will be reverted after a boot. You have to write into config files in /etc/ to make these changes permanent

dev

udev controls /dev/ directory. There are abstracted devices like a hard, is /dev/sda or /dev/hd0 regardless of its brand, model or technology:

root@funlife:/dev# ls /dev/sda*
/dev/sda  /dev/sda1  /dev/sda2  /dev/sda3  /dev/sda5  /dev/sda6

lsmod, lsusb, lspci

These commands show list of modules and hardwares on the system.

lsmod

Shows kernel modules.

root@funlife:/dev# lsmod
Module                  Size  Used by
pci_stub               12622  1 
vboxpci                23256  0 
vboxnetadp             25670  0 
vboxnetflt             27605  0 
vboxdrv               418013  3 vboxnetadp,vboxnetflt,vboxpci
ctr                    13049  3 
ccm                    17731  3 
dm_crypt               23172  1 
bnep                   19543  2 
rfcomm                 69509  8 
uvcvideo               81065  0 
arc4                   12608  2 
videobuf2_vmalloc      13216  1 uvcvideo
intel_rapl             18783  0 
iwldvm                236430  0 
x86_pkg_temp_thermal    14205  0 
intel_powerclamp       18786  0 
btusb                  32448  0 
videobuf2_memops       13362  1 videobuf2_vmalloc
videobuf2_core         59104  1 uvcvideo
v4l2_common            15682  1 videobuf2_core
mac80211              660592  1 iwldvm
coretemp               13441  0 
videodev              149725  3 uvcvideo,v4l2_common,videobuf2_core
media                  21963  2 uvcvideo,videodev
bluetooth             446190  22 bnep,btusb,rfcomm
kvm_intel             143592  0 
kvm                   459835  1 kvm_intel
snd_hda_codec_hdmi     47547  1 
crct10dif_pclmul       14307  0 
6lowpan_iphc           18702  1 bluetooth
crc32_pclmul           13133  0 
snd_hda_codec_conexant    23064  1 
ghash_clmulni_intel    13230  0 
snd_hda_codec_generic    68914  1 snd_hda_codec_conexant
aesni_intel           152552  10 
snd_seq_midi           13564  0 
snd_seq_midi_event     14899  1 snd_seq_midi
aes_x86_64             17131  1 aesni_intel
mei_me                 19742  0 
lrw                    13287  1 aesni_intel
iwlwifi               183038  1 iwldvm

These are the kernel modules which are loaded.

If you need to add a module to your kernel (say a new driver for a hardware) or remove it (uninstall a driver) you can use rmmod and modprobe.

# rmmod iwlwifi

And this is for installing the module:

# insmod kernel/drivers/net/wireless/lwlwifi.ko

but nobody uses insmod because it does not understand dependencies and you need to give it the whole path to the module file. Instead, use the modprobe command:

# modprobe iwlwifi

you can use -f switch to FORCE rmmod to remove the module even if it is in use.

If you need to load some modules every time your system boots, do one of the following:

add their names to this file /etc/modules
add their configs files to the /etc/modprobe.d/

lspci

Shows PCI devices that are connected to the computer.

# lspci
00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09)
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
00:16.0 Communication controller: Intel Corporation 6 Series/C200 Series Chipset Family MEI Controller #1 (rev 04)
00:19.0 Ethernet controller: Intel Corporation 82579LM Gigabit Network Connection (rev 04)
00:1a.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #2 (rev 04)
00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 04)
00:1c.0 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 1 (rev b4)
00:1c.1 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 2 (rev b4)
00:1c.4 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 5 (rev b4)
00:1d.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #1 (rev 04)
00:1f.0 ISA bridge: Intel Corporation QM67 Express Chipset Family LPC Controller (rev 04)
00:1f.2 SATA controller: Intel Corporation 6 Series/C200 Series Chipset Family 6 port SATA AHCI Controller (rev 04)
00:1f.3 SMBus: Intel Corporation 6 Series/C200 Series Chipset Family SMBus Controller (rev 04)
03:00.0 Network controller: Intel Corporation Centrino Wireless-N 1000 [Condor Peak]
0d:00.0 System peripheral: Ricoh Co Ltd MMC/SD Host Controller (rev 07)

lsusb

Shows all the USB devices connected to the system.

# lsusb
Bus 002 Device 003: ID 1c4f:0026 SiGma Micro Keyboard
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 005: ID 04f2:b217 Chicony Electronics Co., Ltd Lenovo Integrated Camera (0.3MP)
Bus 001 Device 004: ID 0a5c:217f Broadcom Corp. BCM2045B (BDC-2.1)
Bus 001 Device 003: ID 192f:0916 Avago Technologies, Pte. 
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

lspcmcia

Shows available PCMCIA cards on this computer.

lshal

Shows HAL data.

lshw

Shows hardware. Test it!

Device UUIDs

Each device has an ID. If you speak about /dev/sda, you are speaking about the "first hard" but if you want a specific drive to be your /home, you have to use UUID.

root@funlife:/dev# cat /proc/mounts 
rootfs / rootfs rw 0 0
sysfs /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
udev /dev devtmpfs rw,relatime,size=4014804k,nr_inodes=1003701,mode=755 0 0
devpts /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
tmpfs /run tmpfs rw,nosuid,noexec,relatime,size=806028k,mode=755 0 0
/dev/disk/by-uuid/1651a94e-0b4e-47fb-aca0-f77e05714617 / ext4 rw,relatime,errors=remount-ro,data=ordered 0 0

Every other device has its own ID which can be used to identify it.

hotplug

Hotplug is when you insert a hardware into a running computer and coldplug is when you have to turn your computer off to install a hardware. USB devices are hot pluggable while PCI cards should be cold-plugged.

101.1. Determine and configure hardware settings