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diff --git a/Documentation/nfsroot.txt b/Documentation/nfsroot.txt deleted file mode 100644 index a87d4af216c..00000000000 --- a/Documentation/nfsroot.txt +++ /dev/null @@ -1,210 +0,0 @@ -Mounting the root filesystem via NFS (nfsroot) -=============================================== - -Written 1996 by Gero Kuhlmann <gero@gkminix.han.de> -Updated 1997 by Martin Mares <mj@atrey.karlin.mff.cuni.cz> - - - -If you want to use a diskless system, as an X-terminal or printer -server for example, you have to put your root filesystem onto a -non-disk device. This can either be a ramdisk (see initrd.txt in -this directory for further information) or a filesystem mounted -via NFS. The following text describes on how to use NFS for the -root filesystem. For the rest of this text 'client' means the -diskless system, and 'server' means the NFS server. - - - - -1.) Enabling nfsroot capabilities - ----------------------------- - -In order to use nfsroot you have to select support for NFS during -kernel configuration. Note that NFS cannot be loaded as a module -in this case. The configuration script will then ask you whether -you want to use nfsroot, and if yes what kind of auto configuration -system you want to use. Selecting both BOOTP and RARP is safe. - - - - -2.) Kernel command line - ------------------- - -When the kernel has been loaded by a boot loader (either by loadlin, -LILO or a network boot program) it has to be told what root fs device -to use, and where to find the server and the name of the directory -on the server to mount as root. This can be established by a couple -of kernel command line parameters: - - -root=/dev/nfs - - This is necessary to enable the pseudo-NFS-device. Note that it's not a - real device but just a synonym to tell the kernel to use NFS instead of - a real device. - - -nfsroot=[<server-ip>:]<root-dir>[,<nfs-options>] - - If the `nfsroot' parameter is NOT given on the command line, the default - "/tftpboot/%s" will be used. - - <server-ip> Specifies the IP address of the NFS server. If this field - is not given, the default address as determined by the - `ip' variable (see below) is used. One use of this - parameter is for example to allow using different servers - for RARP and NFS. Usually you can leave this blank. - - <root-dir> Name of the directory on the server to mount as root. If - there is a "%s" token in the string, the token will be - replaced by the ASCII-representation of the client's IP - address. - - <nfs-options> Standard NFS options. All options are separated by commas. - If the options field is not given, the following defaults - will be used: - port = as given by server portmap daemon - rsize = 1024 - wsize = 1024 - timeo = 7 - retrans = 3 - acregmin = 3 - acregmax = 60 - acdirmin = 30 - acdirmax = 60 - flags = hard, nointr, noposix, cto, ac - - -ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf> - - This parameter tells the kernel how to configure IP addresses of devices - and also how to set up the IP routing table. It was originally called `nfsaddrs', - but now the boot-time IP configuration works independently of NFS, so it - was renamed to `ip' and the old name remained as an alias for compatibility - reasons. - - If this parameter is missing from the kernel command line, all fields are - assumed to be empty, and the defaults mentioned below apply. In general - this means that the kernel tries to configure everything using both - RARP and BOOTP (depending on what has been enabled during kernel confi- - guration, and if both what protocol answer got in first). - - <client-ip> IP address of the client. If empty, the address will either - be determined by RARP or BOOTP. What protocol is used de- - pends on what has been enabled during kernel configuration - and on the <autoconf> parameter. If this parameter is not - empty, neither RARP nor BOOTP will be used. - - <server-ip> IP address of the NFS server. If RARP is used to determine - the client address and this parameter is NOT empty only - replies from the specified server are accepted. To use - different RARP and NFS server, specify your RARP server - here (or leave it blank), and specify your NFS server in - the `nfsroot' parameter (see above). If this entry is blank - the address of the server is used which answered the RARP - or BOOTP request. - - <gw-ip> IP address of a gateway if the server is on a different - subnet. If this entry is empty no gateway is used and the - server is assumed to be on the local network, unless a - value has been received by BOOTP. - - <netmask> Netmask for local network interface. If this is empty, - the netmask is derived from the client IP address assuming - classful addressing, unless overridden in BOOTP reply. - - <hostname> Name of the client. If empty, the client IP address is - used in ASCII notation, or the value received by BOOTP. - - <device> Name of network device to use. If this is empty, all - devices are used for RARP and BOOTP requests, and the - first one we receive a reply on is configured. If you have - only one device, you can safely leave this blank. - - <autoconf> Method to use for autoconfiguration. If this is either - 'rarp' or 'bootp', the specified protocol is used. - If the value is 'both' or empty, both protocols are used - so far as they have been enabled during kernel configura- - tion. 'off' means no autoconfiguration. - - The <autoconf> parameter can appear alone as the value to the `ip' - parameter (without all the ':' characters before) in which case auto- - configuration is used. - - - - -3.) Kernel loader - ------------- - -To get the kernel into memory different approaches can be used. They -depend on what facilities are available: - - -3.1) Writing the kernel onto a floppy using dd: - As always you can just write the kernel onto a floppy using dd, - but then it's not possible to use kernel command lines at all. - To substitute the 'root=' parameter, create a dummy device on any - linux system with major number 0 and minor number 255 using mknod: - - mknod /dev/boot255 c 0 255 - - Then copy the kernel zImage file onto a floppy using dd: - - dd if=/usr/src/linux/arch/i386/boot/zImage of=/dev/fd0 - - And finally use rdev to set the root device: - - rdev /dev/fd0 /dev/boot255 - - You can then remove the dummy device /dev/boot255 again. There - is no real device available for it. - The other two kernel command line parameters cannot be substi- - tuted with rdev. Therefore, using this method the kernel will - by default use RARP and/or BOOTP, and if it gets an answer via - RARP will mount the directory /tftpboot/<client-ip>/ as its - root. If it got a BOOTP answer the directory name in that answer - is used. - - -3.2) Using LILO - When using LILO you can specify all necessary command line - parameters with the 'append=' command in the LILO configuration - file. However, to use the 'root=' command you also need to - set up a dummy device as described in 3.1 above. For how to use - LILO and its 'append=' command please refer to the LILO - documentation. - -3.3) Using loadlin - When you want to boot Linux from a DOS command prompt without - having a local hard disk to mount as root, you can use loadlin. - I was told that it works, but haven't used it myself yet. In - general you should be able to create a kernel command line simi- - lar to how LILO is doing it. Please refer to the loadlin docu- - mentation for further information. - -3.4) Using a boot ROM - This is probably the most elegant way of booting a diskless - client. With a boot ROM the kernel gets loaded using the TFTP - protocol. As far as I know, no commercial boot ROMs yet - support booting Linux over the network, but there are two - free implementations of a boot ROM available on sunsite.unc.edu - and its mirrors. They are called 'netboot-nfs' and 'etherboot'. - Both contain everything you need to boot a diskless Linux client. - - - - -4.) Credits - ------- - - The nfsroot code in the kernel and the RARP support have been written - by Gero Kuhlmann <gero@gkminix.han.de>. - - The rest of the IP layer autoconfiguration code has been written - by Martin Mares <mj@atrey.karlin.mff.cuni.cz>. - - In order to write the initial version of nfsroot I would like to thank - Jens-Uwe Mager <jum@anubis.han.de> for his help. |