Ten boot time parameters you should know about the Linux Kernel__linux

The Linux kernel accepts boot time parameters as it starts to boot system. This is used to inform kernel about various hardware parameter. Need boot time Parameters:

* Troubleshoot system
* Hardware Parameters The kernel would not able to determine on its own
* Force kernel to override of the default hardware parameters in order to increase performance
* Password and other recovery operations the kernel command line Syntax

Name=value1,value2,value3 ...

Where, Name:keyword name, for example, init, RO, boot etc Ten common boot time parameters init

This sets the initial command to is executed by the kernel. The Default is to Use/sbin/init, which are the parent of all processes.
To boot system without password Pass/bin/bash or/bin/sh as argument to Init
Init=/bin/bash Single

The most common argument that's passed to the INIT process are the word ' single ' which instructs Init to boot the computer In single user mode, and not launch all usual daemons root=/dev/device

This argument tells the kernel what device (hard disk, floppy disk) to is used as the root filesystem while booting. For example following boot parameter use/dev/sda1 as the root file system:
Root=/dev/sda1

If you copy entire partition from/dev/sda1 TO/DEV/SDB1 then use
ROOT=/DEV/SDB1 ro

This argument tells the kernel to mount root file system as read-only. This is do so the FSCK program can check and repair a Linux file system. Please should never ever run fsck on Read/write file system. RW

This argument tells the kernel to mount root file system as read and write mode. Panic=second

Specify kernel behavior on panic. By default, the kernel won't reboot after a panic, but this option would cause a kernel reboot after N seconds. For example following boot parameter'll force to reboot Linux after seconds
panic=10 Maxcpus=number

Specify maximum number of processors that a SMP kernel should make use of. For example if your have four CPUs and would like-to-use 2 CPUs then pass 2 as a # to Maxcpus (useful to test different Software performances and configurations).
maxcpus=2 Debug

Enable kernel debugging. This option is useful for kernel hackers and developers who wish to troubleshoot problem SELinux [0|1]

Disable or enable SELinux at the boot time. Value 0:disable selinux value 1:enable selinux raid=/dev/mdn

This argument tells kernel howto assembly of RAID arrays in boot time. The kernel (not as module), partitions of type 0xfd are scanned and Automaticall Y assembled into RAID arrays. This autodetection is suppressed with the kernel parameter "Raid=noautodetect". As of kernel 2.6.9, only drives with a type 0 Superblock can is autodetected and run at boot time. mem=memeory_size

This is a classic parameter. Force usage of a specific amount of memory to being used when the kernel was not able to, the whole system memory or for TE St. For example:
mem=1024m

The kernel command line was a null-terminated string currently up to 255 characters long, plus the final null. A string, is too long would be automatically truncated by the kernel, a boot loader could allow a longer command line to Be passed to permit future kernels to extend this limit (H. Peter anvin). Other parameters initrd/boot/initrd.img

An INITRD should is loaded. The boot process would load the kernel and an initial ramdisk; Then the kernel converts initrd into a ' normal ' ramdisk, which is mounted read-write as root device; THEN/LINUXRC is executed; Afterwards the ' real ' root file system is mounted, and the Initrd file system are moved over TO/INITRD; Finally the usual boot sequence (e.g. invocation of/sbin/init) is performed. INITRD is used to provide/load additional modules (device driver). For example, SCSI or RAID device driver loaded using INITRD. HDX =noprobe

Don't probe for HDX drive. For example, disable HDB hard disk:
Hdb=noprobe

If You are disable HDB in BIOS, Linux would still detect it. This is the only way to disable HDB. Ether=irq,iobase,[arg1,arg2],name

Where, Ether:ethernet DEVICES

For example, following boot argument force probing for a second Ethernet card (NIC), as the "to" Probe for O NE (irq=0,iobase=0 means automatically detect them).
Ether=0,0,eth1 to begin the Enter parameters mode?

You are need to enter the all this parameter in Grub or Lilo boot prompt. For example if your are using Grub as a boot loader, at the grub prompt press ' e ' to edit command before booting.

1) Select second line
2) Again, press ' E ' to edit selected command
3) Type any of above parameters.

Example of "Recovering Grub boot loader password" For more information. Another option is to-type above parameters in grub.conf or lilo.conf file itself.

The complete list of Linux kernel parameters i.e./usr/src/linux/documentation/kernel-parameters.txt file.