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Kernel 2.6 are expecting the {{{initrd}}} file to be a (compressed) cpio archive, to be uncompressed in a ramdisk, known as ''initramfs''. Debian automatically use initramfs-tools or yaird to create and/or update an appropriate initrd for the system. Kernel 2.6 is expecting the {{{initrd}}} file to be a (compressed) cpio archive, to be uncompressed in a ramdisk, known as ''initramfs''. Debian automatically uses initramfs-tools or yaird to create and/or update an appropriate initrd for the system.
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For example, you can change the driver-policy by setting MODULES=most to MODULES=dep there. This will cause the system to include only the drivers the system is aware of to need (instead of simply including most of them). However, be aware that there is a slightly chance that a needed driver isn't included and your system may fail to boot.
The driver-policy (''MODULES''-option) can be overridden by a file ''driver-policy'' put into /etc/initramfs-tools/conf.d/.
For example, you can change the driver policy by setting MODULES=most to MODULES=dep there. This will cause the system to include only the drivers the system is aware of to need (instead of simply including most of them). However, be aware of a slightly chance that a needed driver isn't included and your system may fail to boot.
The driver policy (''MODULES''-option) can be overridden by a file named ''driver-policy'' put into /etc/initramfs-tools/conf.d/.

Translation(s): English - Français - Italiano


initrd provides the capability to load a RAM disk by the boot loader. This RAM disk can then be mounted as the root file system and programs can be run from it. Afterwards, a new root file system can be mounted from a different device. The previous root (from initrd) is then moved to a directory and can be subsequently unmounted.

initrd is mainly designed to allow system startup to occur in two phases, where the kernel comes up with a minimum set of compiled-in drivers, and where additional modules are loaded from initrd.(abstract from http://www.kernel.org/doc/Documentation/kernel-parameters.txt)

  • The initrd files are usually in /boot directory, named /boot/initrd.img-kversion with a /initrd.img being a symbolic link to the latest installed initrd.

  • The typical Debian user should not care about the initrd because it is created automatically at kernel image'd post-installation time. Anyway you can configure the behaviour of this process with the file /etc/kernel-img.conf. Note: If it works, do not touch it.

initrd kernel parameter

The initrd=filename kernel parameter Specify the location of the initial ramdisk (which can be either a plain 2.4's initrd or a 2.6's initramfs).

Initramfs image (kernel >= 2.6)

Kernel 2.6 is expecting the initrd file to be a (compressed) cpio archive, to be uncompressed in a ramdisk, known as initramfs. Debian automatically uses initramfs-tools or yaird to create and/or update an appropriate initrd for the system.

If you're using initramfs-tools, you can configure it and hence change what is put into the initrd by editing /etc/initramfs-tools/initramfs.conf or putting files into /etc/initramfs-tools/conf.d/ overriding /etc/initramfs-tools/initramfs.conf. For example, you can change the driver policy by setting MODULES=most to MODULES=dep there. This will cause the system to include only the drivers the system is aware of to need (instead of simply including most of them). However, be aware of a slightly chance that a needed driver isn't included and your system may fail to boot. The driver policy (MODULES-option) can be overridden by a file named driver-policy put into /etc/initramfs-tools/conf.d/.

Initrd image (kernel <=2.4)

  • {i} kernel 2.4 is now obsolete, legacy initrd too !

Kernel up to 2.4 were expecting the initrd file to be a (compressed) block-disk image (i.e formated as ext2 or minix fs). the initrd was created using mkinitrd.

See Also


CategoryBootProcess