Specifications

The `rootflags=' Argument
This option allows you to give options pertaining to the mounting of the root filesystem just as you would to
the mount program. An example could be giving the noatime option to an ext2 fs.
The `rootfstype=' Argument
This option allows you to give a comma separated list of fs types that will be tried for a match when trying to
mount the root filesystem. This list will be used instead of the internal default which usually starts with ext2,
minix and the like.
The `ro' Argument
When the kernel boots, it needs a root filesystem to read basic things off of. This is the root filesystem that is
mounted at boot. However, if the root filesystem is mounted with write access, you can not reliably check the
filesystem integrity with half−written files in progress. The `ro' option tells the kernel to mount the root
filesystem as `readonly' so that any filesystem consistency check programs (fsck) can safely assume that there
are no half−written files in progress while performing the check. No programs or processes can write to files
on the filesystem in question until it is `remounted' as read/write capable.
This is one of the few kernel boot arguments that has its default stored in the kernel image, and which can thus
be altered with the rdev utility.
The `rw' Argument
This is the exact opposite of the above, in that it tells the kernel to mount the root filesystem as read/write.
The default is to mount the root filesystem as read only. Do not run any `fsck' type programs on a filesystem
that is mounted read/write.
The same value stored in the image file mentioned above is also used for this parameter, accessible via rdev.
The `nfsroot=' Argument
This argument tells the kernel which machine, what directory and what NFS options to use for the root
filesystem. Also note that the argument root=/dev/nfs is required. Detailed information on using an NFS
root fs is in the file linux/Documentation/nfsroot.txt.
The `ip=' or `nfsaddrs=' Argument
If you are using NFS as a root filesystem, then there is no programs like ifconfig and route present until
the root fs is mounted, and so the kernel has to configure the network interfaces directly. This boot argument
sets up the various network interface addresses that are required to communicate over the network. If this
argument is not given, then the kernel tries to use RARP and/or BOOTP to figure out these parameters.
3.2 Options Relating to RAM Disk Management
The following options all relate to how the kernel handles the RAM disk device, which is usually used for
bootstrapping machines during the install phase, or for machines with modular drivers that need to be installed
to access the root filesystem.
The Linux BootPrompt−HowTo
The `rootflags=' Argument 8