Kernel of Linux system start-up process

Kernel of Linux system start-up process

1, the kernel parameter modification method:

2, within Core kernel module management:

3, within Nuclear compilation

How user space accesses and monitors the kernel:/proc,/sys

Pseudo file System

/proc/sys: Many of the files in this directory are readable and writable

/sys/: Some files can be written

1, the kernel parameter modification method:

echo VALUE >/proc/sys/to/somefile

Sysctl-w kernel.hostname=

[[email protected] vm]# free-m
  total   used    free   shared    buffers     Cached
mem:     7983  541  7442  0  149  269
-/+ buffers/cache:  123   7860
Swap:& nbsp;   4094    0 4094
[[email protected] Vm]# echo 1 >/proc/sys/vm/drop_caches
[[email protected] vm]# free-m
 total  used & nbsp free  shared  buffers   Cached
mem:  7983  125   7857   0  0   9
-/+ buffers/cache:115  7867
swap:4094  0  4094

[Email protected] kernel]# sysctl-w Vm.drop_caches=1
Vm.drop_caches = 1
[Email protected] kernel]# free-m
Total used free shared buffers Cached
mem:7983 7857 0 0 9
-/+ buffers/cache:115 7868
swap:4094 0 4094

[Email protected] kernel]# cat /proc/sys/kernel/hostname
Localhost.localdomain
[Email protected] kernel]# echo wfx >/proc/sys/kernel/hostname
[Email protected] kernel]# hostname
Wfx

[Email protected] kernel]# sysctl-w kernel.hostname= "local.com"
Kernel.hostname = local.com
[Email protected] kernel]# hostname
Local.com

[Email protected] kernel]# cat /proc/sys/net/ipv4/ip_forward
0

[[email protected] kernel]# vim /etc/sysctl.conf # modified file permanently valid, but not immediately effective

# Kernel sysctl configuration file for Red Hat Linux

# for binary values, 0 are disabled, 1 is enabled. See Sysctl (8) and
# sysctl.conf (5) for more details.
# Controls IP Packet forwarding
Net.ipv4.ip_forward = 1 # 0 modified to 1
...

[[email protected] kernel]# sysctl-p # Immediate effect
Net.ipv4.ip_forward = 1
Net.ipv4.conf.default.rp_filter = 1
Net.ipv4.conf.default.accept_source_route = 0
KERNEL.SYSRQ = 0

[[email protected] kernel]# cat /proc/sys/net/ipv4/ip_forward # Verification
1

[Email protected] kernel]# sysctl-a |wc-l #显示所有内核参数及其值
635

2, within Core kernel module management:

Lsmod: View

Modprobe mod_name: Loading a module

Modprobe-r mod_name: Uninstalling a module

Modinfo mod_name: View specific information about the module

Insmod/path/to/module_file: Load Module

Rmmod mod_name: Uninstalling a module

Depmod/path/to/modiles_dir the kernel module must be the same version when installing the driver

[Email protected] kernel]# lsmod |grep Floppy
Floppy 95465 0
[Email protected] kernel]#Modprobe-rFloppy #删除模块floppy
[Email protected] kernel]# lsmod |grep Floppy
[Email protected] kernel]#modprobeFloppy #加载模块floppy
[Email protected] kernel]# lsmod |grep Floppy
Floppy 95465 0
[Email protected] kernel]#ModinfoFloppy
Filename:/lib/modules/2.6.18-164.el5/kernel/drivers/block/floppy.ko#file path
alias:block-major-2-*
License:gpl#License
Author:alain L. Knaff
srcversion:f532f52860888e835bb857c
depends:#No dependent modules
Vermagic:2.6.18-164.el5 SMP mod_unload gcc-4.1
Parm:floppy:charp
Parm:FLOPPY_IRQ:int
Parm:FLOPPY_DMA:int
Module_sig : 883f3504a8b7cf4bd273d74512bb1123df09e372bd75c92d020dd4b4fc61c617dd1534e826ec209f4bf9199f6f44b9471d2683a52c2b99aead71e

[[email protected] kernel]# modprobe-r floppy # Delete module floppy
[[email protected] kernel]# insmod floppy # mount module, instead of specifying a name, specify the file name path
Insmod:can ' t read ' floppy ': No such file or directory
[Email protected] kernel]# insmod /lib/modules/2.6.18-164.el5/kernel/drivers/block/floppy.ko
[[email protected] kernel]# lsmod |grep Floppy # Verify loading Module floppy success
Floppy 95465 0
[[email protected] kernel]# rmmod Floppy # Remove Module Floppy Method two
[Email protected] kernel]# lsmod |grep Floppy
[Email protected] kernel]#

3, within Nuclear compilation

Features in the kernel, in addition to the core functions, at compile time, most of the features have three choices:

1, do not use this function;

2, compile into kernel module;

3, compile into the kernel;

How to manually compile the kernel:

Make Gconfig:gnome desktop environment, need to install the Graphics Development Library Group: GNOME softwaredevelopment

Make KCONFIG:KDE desktop environment, need to install graphics development Library

[Email protected] yum.repos.d]#Yum grouplist
Loaded Plugins:rhnplugin, security
Repository CD-ROM is listed more than once in the configuration
This system isn't registered with the portal.
Portal support would be disabled.
Setting up Group Process
Cd-rom/group | 1.0 MB 00:00
Installed Groups:
...
Available Groups:
Authoring and Publishing
Development Libraries
Development Tools
...

[email protected] linux]# Yum groupinstall "Development Tools" "Development Libraries"-y

Running time: 10-100min

[email protected] yum.repos.d]# Yum grouplist
Installed Groups:

Development Libraries
Development Tools

...
Available Groups:
Authoring and Publishing
...

Kernel pack: https://www.kernel.org/pub/linux/kernel/v2.6/

14-aug-2004 11:13 43M

[Email protected] ~]# tar XF linux-2.6.8.1.tar.gz-c/usr/src/
[Email protected] ~]# cd/usr/src/
[[email protected] src]# ls
Kernels Linux linux-2.6.8.1 Redhat
[Email protected] src]# LN-SV linux-2.6.8.1 Linux
' linux/linux-2.6.8.1 ', ' linux-2.6.8.1 '
[[email protected] src]# ls
Kernels Linux linux-2.6.8.1 Redhat
[[Email protected] src]# CD Linux

[Email protected] linux]# Ls-al
...
-rw-r--r--1 root root 79210 2007-10-31 02:01. config

...

[Email protected] linux]# Cp/boot/config-2.6.23.1-42.fc8/usr/src/linux/.config
Cp:overwrite '/usr/src/linux/.config '? Y

[[email protected] linux]# ls-al # make two edits with native kernel version files to reduce the error rate

...

-rw-r--r--1 root root 79210 2016-11-19 15:49. config

...

[email protected] linux]# make menuconfig #必须在linux目录下执行后进入文本模式

30min--5h the edited settings into the. config

650) this.width=650; "Src=" Http://s3.51cto.com/wyfs02/M00/8A/6F/wKioL1gwBWfg4rW6AABtMjCyfVY249.png-wh_500x0-wm_3 -wmp_4-s_711200342.png "title=" compile kernel. png "alt=" wkiol1gwbwfg4rw6aabtmjcyfvy249.png-wh_50 "/>

1th step, make Menuconfig: Open the graphics window under text

2nd step, make

3rd Step, make Modules_install

4th step, make install

Screen command: The connection can be broken and opened again

Screen-ls: Displays the already established screen

Screen: Open a new display directly

CTRL + A, D: Remove screen, can restore back

Screen-r ID: Revert back to a screen

Exit: Exit

[email protected] linux]# Yum install screen

[R[email protected] ~]# Screen-ls
There is screens on:
8231.pts-4.fox (Detached)
8200.pts-0.fox (Detached)
2 Sockets in/var/run/screen/s-root.
[Email protected] ~]# screen-r 8231

Two compile-time cleanup, before cleaning, back up the configuration file, if necessary. config:

Making clean cleans up the prepared binary modules

Make Mrproper clears all remaining files, including the. config file

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Kernel of Linux system start-up process