Workbook 2: Hardware and Device Configuration

Question 1

What is a device driver? [5]

Answer 1

hardware, such as network interface cards, USB devices, and disks, use more specialized components of the kernel referred to as device drivers.

Question 2

What is a static kernel image?

Answer 2

The static kernel image is the file that is loaded when your system is booted. lives in the /boot directory

Question 3

What is the name of the static kernel image?

Answer 3

name vmlinuz-version

Question 4

How can you determine which command line was used to boot the current instance of the kernel

Answer 4

When read, the file /proc/cmdline reports the command line that was used to boot the current instance of the kernel.
[root@station root]# cat /proc/cmdline
ro root=LABEL=/ vga=0x317

Question 5

What is a kernel module? [6]

Answer 5

Supplementary device drivers (which are not needed during the initial stages of system booting), such as network interface drivers and sound card drivers, are usually implemented as kernel modules

Question 6

Where are kernel modules stored in the filesystem? [6]

Answer 6

usually underneath the directory /lib/modules/version

Question 7

What command generates a list of currently loaded kernel modules? [6]

Answer 7

The lsmod command

Question 8

How can parameters be passed to modular device drivers as they are loaded? [6]

Answer 8

Whenever a module is loaded “on demand” by the kernel, the file /etc/modprobe.conf is examined for module parameters

Question 9

What does the dmesg buffer contain? [7]

Answer 9

all messages emitted by the kernel, are stored in a dynamic kernel buffer referred to as the dmesg buffer. The dmesg buffer is a “ring buffer”.

Question 10

What command outputs the current contents of the dmesg buffer? [8]

Answer 10

The current contents of the dmesg buffer can be dumped to standard out with the dmesg command.

Question 11

Where can a snapshot of the dmesg buffer be found? [8]

Answer 11

a snapshot of the dmesg buffer is recorded in the file /var/log/dmesg.

Question 12

What does the kudzu utility do? [8]

Answer 12

The kudzu utility is a bootup utility that detects newly added or removed hardware, and configures the machine appropriately

Question 13

What is the absolute reference of the file that contains a dynamic database of currently detected hardware? [9]

Answer 13

The first, /etc/sysconfig/hwconf is

a dynamic database of currently detected hardware.

Question 14

Give a command line that can be used to monitor hardware changed dynamically. [10]

Answer 14

The lshal command can also be used to monitor hardware changed dynamically, by adding a -m
command line switch.

Question 15

What is the /proc filesystem? [11]

Answer 15

resource for determining hardware configuration is the proc filesystem.

Question 16

Does Linux support SMP? [12]

Answer 16

Linux supports symmetric multiple processing, with support for up to 32 CPU’s, though more than 8 is seldom implemented in the x86 architecture.

Question 17

What is the absolute reference of the file that reports information about detected CPUs? [12]

Answer 17

The proc filesystem file /proc/cpuinfo reports information about detected CPU(s).

Question 18

What is the absolute reference of the file that provides statistics about the amount of detected memory and current memory utilization? [13]

Answer 18

The proc filesystem file /proc/meminfo provides statistics about the amount of detected memory,

Question 19

What are the naming conventions for 
(i) an IDE primary master disk 
(ii) an IDE primary slave disk 
(iii) an IDE secondary master disk 
(iv) an IDE secondary slave disk?
 [14/15]

Answer 19

1 hda - primary master
2. hdb - primary slave
3 hdc - secondary master
4. hdd secondary slave

Question 20

In which directory can low level information about a primary master IDE disk be found? [15]

Answer 20

The proc filesystem directory /proc/ide contains subdirectories for every detected IDE drive

Question 21

How does Linux usually refer to the first detected SCSI or SATA disk? [16]

Answer 21

Linux usually refers to the first detected SCSI drive as sda, the second drive as sdb, and so on.

Question 22

What command lists all attached PCI devices? [23]

Answer 22

The lspci command can be used to list all attached PCI devices.

Question 23

Give a command line that displays the available IRQ lines and any device drivers which are using them. [24]

Answer 23

The proc filesystem file /proc/interrupts displays the available IRQ lines,

Question 24

Give a command line that outputs which ports have been claimed by which device driver. [25]

Answer 24

The proc filesystem file /proc/ioports displays which ports have been claimed by which device driver.

Question 25

Give a command line that outputs all of the devices whose memory buffers have been mapped into physical memory and the physical memory addresses which have been assigned to each buffer. [25]

Answer 25

The proc filesystem file /proc/iomem displays all of the devices whose memory buffers have been mapped into physical memory,

Question 26

What happens when a new PCI device is recognized by the HAL but an appropriate device driver is not already present in the kernel? [26]

Answer 26

appropriate modules for various PCI devices is consulted, found at /lib/modules/2.6.18-8/modules.pcimap

Question 27

What is the purpose of the lspci command’s –v switch? [27]

Answer 27

The lspci, if used with the -v command line switch, will report the resources associated with each device.

Question 28

How do processes communicate with device drivers? [34]

Answer 28

processes communicate with device drivers as if they were files.

Question 29

What are files which reference device drivers referred to as? [35]

Answer 29

device nodes.

Question 30

In which directory are device nodes found? [35]

Answer 30

in a dedicated /dev directory.

Question 31

Give an example of a (i) block device (ii) character device. [35]

Answer 31

1. Block Devices are devices that allow random access, and transfer information in fixed size chucks, or "blocks". 2. Character Devices are devices that don’t interact with the I/O cache

Question 32

In a long listing, what character is used to identify a (i) block device node (ii) character device node? [35]

Answer 32

1. block device nodes are identified by a “b”. | 2. character device nodes are identified by a “c”,

Question 33

What information, if any, is stored in a device node? [35]

Answer 33

Device nodes are not used for storing information. | Instead, they serve as a conduit, transferring information to and from an underlying device driver.

Question 34

Explain the purpose of the major number of a filesystem device node. [36]

Answer 34

The major number of a filesystem device node correlates to the major number of the device driver with which it is associated.

Question 35

What three parameters are used to associate a device node to a particular device driver? [37]

Answer 35

block or character file type major number, minor number.

Question 36

Give a command line to create a device node named mytty4 that can be used to output data to the fourth virtual console. [37/38]

Answer 36

mknod command to create device nodes.

Question 37

What is special about /dev/cdrom? [39]

Answer 37

x

Question 38

Give a command line to backup the MBR of the primary master IDE disk. [40]

Answer 38

[root@station root]# dd if=/dev/hda of=/tmp/MBR.backup bs=512 count=1 1+0 records in

Question 39

Which command returns how long a machine has been operating without powering down or rebooting? [46]

Answer 39

uptime

Question 40

Explain the meaning of the three load averages output by the uptime command? [46] 08:14:10 up 1:28, 4 users, load average: 0.56, 0.23, 0.12

Answer 40

A 1 minute average, a 5 minute average, and a 15 minute average).

Question 41

Which command gives a dynamic output of processes running on a machine? [46]

Answer 41

cat /proc/meminfo

Question 42

By default, how often is the top command’s output refreshed? [46]

Answer 42

The list is refreshed about every five seconds.

Question 43

Refer to the output on the top of page 49. Explain the significance of the values labelled 1 and 2. [49]

Answer 43

Recall the MemTotal line

Question 44

Refer to the top command’s output in the middle of page 49. Explain the significance of the values labelled 1 through 5. [49]

Answer 44

1: Total Physical Memory 2. Available Memory is currently in use 3. Available Memory is currently available 4 & 5 : How much memory is currently being used to cache disk