Red Hat LINUX 7.2 - OFFICIAL LINUX CUSTOMIZATION GUIDE Guida di Installazione Scaricare il pdf (Pagina 26)

26 Chapter 2. The /proc File System

occasionally compiled for particular architectures, this value tells you which package to install on

the system.

• model name — Gives you the popular name of the processor, including its project name.

• cpu MHz — Shows the precise speed in megahertz of that particular processor (in thousandths).

• cache size — Tells you the amount of level 2 memory cache available to the processor.

• flags — Deﬁnes a number of different qualities about the processor, such as the presence of a

ﬂoating point unit (FPU) and the ability to process MMX instructions.

2.2.4. /proc/devices

This ﬁle displays the various character and block devices currently conﬁgured for use with the kernel.

It does not include modules that are available but not loaded into the kernel. Below is a sample output

from this virtual ﬁle:

Character devices:

1 mem

2 pty

3 ttyp

4 ttyS

5 cua

7 vcs

10 misc

14 sound

29 fb

36 netlink

128 ptm

129 ptm

136 pts

137 pts

162 raw

254 iscsictl

Block devices:

1 ramdisk

2 fd

3 ide0

9 md

22 ide1

The output from /proc/devices includes the major number and name of the device.

Character devices are similar to block devices, except for two basic differences.

Block devices have a buffer available, allowing them to order requests before dealing with them. This

is important for devices designed to store information — such as hard drives — because the ability

to order the information before writing it to the device allows it to be placed in more efﬁcient order.

Character devices do not require buffering.

The other difference is that block devices can send and receive information in blocks of a size conﬁg-

ured per device. Character devices send data with no preconﬁgured size.

For more information about devices see /usr/src/linux-2.4/Documentation/devices.txt.

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