From: J. Bruce Fields Date: Mon, 7 Apr 2008 19:59:03 +0000 (-0400) Subject: Documentation: move nfsroot.txt to filesystems/ X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=6ded55da6be9f186ae1022724a5881b43846c164;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git Documentation: move nfsroot.txt to filesystems/ Documentation/ is a little large, and filesystems/ seems an obvious place for this file. Signed-off-by: J. Bruce Fields Signed-off-by: Jonathan Corbet --- diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX index fc8e7c7d182f..08a39cdb27f2 100644 --- a/Documentation/00-INDEX +++ b/Documentation/00-INDEX @@ -271,8 +271,6 @@ netlabel/ - directory with information on the NetLabel subsystem. networking/ - directory with info on various aspects of networking with Linux. -nfsroot.txt - - short guide on setting up a diskless box with NFS root filesystem. nmi_watchdog.txt - info on NMI watchdog for SMP systems. nommu-mmap.txt diff --git a/Documentation/filesystems/00-INDEX b/Documentation/filesystems/00-INDEX index e731196410b3..2ec174c992f1 100644 --- a/Documentation/filesystems/00-INDEX +++ b/Documentation/filesystems/00-INDEX @@ -66,6 +66,8 @@ mandatory-locking.txt - info on the Linux implementation of Sys V mandatory file locking. ncpfs.txt - info on Novell Netware(tm) filesystem using NCP protocol. +nfsroot.txt + - short guide on setting up a diskless box with NFS root filesystem. ntfs.txt - info and mount options for the NTFS filesystem (Windows NT). ocfs2.txt diff --git a/Documentation/filesystems/nfsroot.txt b/Documentation/filesystems/nfsroot.txt new file mode 100644 index 000000000000..31b329172343 --- /dev/null +++ b/Documentation/filesystems/nfsroot.txt @@ -0,0 +1,270 @@ +Mounting the root filesystem via NFS (nfsroot) +=============================================== + +Written 1996 by Gero Kuhlmann +Updated 1997 by Martin Mares +Updated 2006 by Nico Schottelius +Updated 2006 by Horms + + + +In order to use a diskless system, such as an X-terminal or printer server +for example, it is necessary for the root filesystem to be present on a +non-disk device. This may be an initramfs (see Documentation/filesystems/ +ramfs-rootfs-initramfs.txt), a ramdisk (see Documentation/initrd.txt) 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, NFS client support needs to be selected as +built-in during configuration. Once this has been selected, the nfsroot +option will become available, which should also be selected. + +In the networking options, kernel level autoconfiguration can be selected, +along with the types of autoconfiguration to support. Selecting all of +DHCP, BOOTP and RARP is safe. + + + + +2.) Kernel command line + ------------------- + +When the kernel has been loaded by a boot loader (see below) it needs to be +told what root fs device to use. And in the case of nfsroot, where to find +both the server and the name of the directory on the server to mount as root. +This can be established using the following 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=[:][,] + + If the `nfsroot' parameter is NOT given on the command line, + the default "/tftpboot/%s" will be used. + + Specifies the IP address of the NFS server. + The default address is determined by the `ip' parameter + (see below). This parameter allows the use of different + servers for IP autoconfiguration and NFS. + + Name of the directory on the server to mount as root. + If there is a "%s" token in the string, it will be + replaced by the ASCII-representation of the client's + IP address. + + Standard NFS options. All options are separated by commas. + The following defaults are used: + port = as given by server portmap daemon + rsize = 4096 + wsize = 4096 + timeo = 7 + retrans = 3 + acregmin = 3 + acregmax = 60 + acdirmin = 30 + acdirmax = 60 + flags = hard, nointr, noposix, cto, ac + + +ip=:::::: + + 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 + autoconfiguration. + + The parameter can appear alone as the value to the `ip' + parameter (without all the ':' characters before). If the value is + "ip=off" or "ip=none", no autoconfiguration will take place, otherwise + autoconfiguration will take place. The most common way to use this + is "ip=dhcp". + + IP address of the client. + + Default: Determined using autoconfiguration. + + 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. + + Only required for for NFS root. That is autoconfiguration + will not be triggered if it is missing and NFS root is not + in operation. + + Default: Determined using autoconfiguration. + The address of the autoconfiguration server is used. + + IP address of a gateway if the server is on a different subnet. + + Default: Determined using autoconfiguration. + + Netmask for local network interface. If unspecified + the netmask is derived from the client IP address assuming + classful addressing. + + Default: Determined using autoconfiguration. + + Name of the client. May be supplied by autoconfiguration, + but its absence will not trigger autoconfiguration. + + Default: Client IP address is used in ASCII notation. + + Name of network device to use. + + Default: If the host only has one device, it is used. + Otherwise the device is determined using + autoconfiguration. This is done by sending + autoconfiguration requests out of all devices, + and using the device that received the first reply. + + Method to use for autoconfiguration. In the case of options + which specify multiple autoconfiguration protocols, + requests are sent using all protocols, and the first one + to reply is used. + + Only autoconfiguration protocols that have been compiled + into the kernel will be used, regardless of the value of + this option. + + off or none: don't use autoconfiguration + (do static IP assignment instead) + on or any: use any protocol available in the kernel + (default) + dhcp: use DHCP + bootp: use BOOTP + rarp: use RARP + both: use both BOOTP and RARP but not DHCP + (old option kept for backwards compatibility) + + Default: any + + + + +3.) Boot Loader + ---------- + +To get the kernel into memory different approaches can be used. +They depend on various facilities being available: + + +3.1) Booting from a floppy using syslinux + + When building kernels, an easy way to create a boot floppy that uses + syslinux is to use the zdisk or bzdisk make targets which use + and bzimage images respectively. Both targets accept the + FDARGS parameter which can be used to set the kernel command line. + + e.g. + make bzdisk FDARGS="root=/dev/nfs" + + Note that the user running this command will need to have + access to the floppy drive device, /dev/fd0 + + For more information on syslinux, including how to create bootdisks + for prebuilt kernels, see http://syslinux.zytor.com/ + + N.B: Previously it was possible to write a kernel directly to + a floppy using dd, configure the boot device using rdev, and + boot using the resulting floppy. Linux no longer supports this + method of booting. + +3.2) Booting from a cdrom using isolinux + + When building kernels, an easy way to create a bootable cdrom that + uses isolinux is to use the isoimage target which uses a bzimage + image. Like zdisk and bzdisk, this target accepts the FDARGS + parameter which can be used to set the kernel command line. + + e.g. + make isoimage FDARGS="root=/dev/nfs" + + The resulting iso image will be arch//boot/image.iso + This can be written to a cdrom using a variety of tools including + cdrecord. + + e.g. + cdrecord dev=ATAPI:1,0,0 arch/i386/boot/image.iso + + For more information on isolinux, including how to create bootdisks + for prebuilt kernels, see http://syslinux.zytor.com/ + +3.2) Using LILO + When using LILO all the necessary command line parameters may be + specified using the 'append=' directive in the LILO configuration + file. + + However, to use the 'root=' directive you also need to create + a dummy root device, which may be removed after LILO is run. + + mknod /dev/boot255 c 0 255 + + For information on configuring LILO, please refer to its documentation. + +3.3) Using GRUB + When using GRUB, kernel parameter are simply appended after the kernel + specification: kernel + +3.4) Using loadlin + loadlin may be used to boot Linux from a DOS command prompt without + requiring a local hard disk to mount as root. This has not been + thoroughly tested by the authors of this document, but in general + it should be possible configure the kernel command line similarly + to the configuration of LILO. + + Please refer to the loadlin documentation for further information. + +3.5) Using a boot ROM + This is probably the most elegant way of booting a diskless client. + With a boot ROM the kernel is loaded using the TFTP protocol. The + authors of this document are not aware of any no commercial boot + ROMs that support booting Linux over the network. However, there + are two free implementations of a boot ROM, netboot-nfs and + etherboot, both of which are available on sunsite.unc.edu, and both + of which contain everything you need to boot a diskless Linux client. + +3.6) Using pxelinux + Pxelinux may be used to boot linux using the PXE boot loader + which is present on many modern network cards. + + When using pxelinux, the kernel image is specified using + "kernel ". The nfsroot parameters + are passed to the kernel by adding them to the "append" line. + It is common to use serial console in conjunction with pxeliunx, + see Documentation/serial-console.txt for more information. + + For more information on isolinux, including how to create bootdisks + for prebuilt kernels, see http://syslinux.zytor.com/ + + + + +4.) Credits + ------- + + The nfsroot code in the kernel and the RARP support have been written + by Gero Kuhlmann . + + The rest of the IP layer autoconfiguration code has been written + by Martin Mares . + + In order to write the initial version of nfsroot I would like to thank + Jens-Uwe Mager for his help. diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 508e2a2c9864..57709e472b9b 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -845,7 +845,7 @@ and is between 256 and 4096 characters. It is defined in the file arch/alpha/kernel/core_marvel.c. ip= [IP_PNP] - See Documentation/nfsroot.txt. + See Documentation/filesystems/nfsroot.txt. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards See comment before ip2_setup() in @@ -1199,10 +1199,10 @@ and is between 256 and 4096 characters. It is defined in the file file if at all. nfsaddrs= [NFS] - See Documentation/nfsroot.txt. + See Documentation/filesystems/nfsroot.txt. nfsroot= [NFS] nfs root filesystem for disk-less boxes. - See Documentation/nfsroot.txt. + See Documentation/filesystems/nfsroot.txt. nfs.callback_tcpport= [NFS] set the TCP port on which the NFSv4 callback diff --git a/Documentation/nfsroot.txt b/Documentation/nfsroot.txt deleted file mode 100644 index 31b329172343..000000000000 --- a/Documentation/nfsroot.txt +++ /dev/null @@ -1,270 +0,0 @@ -Mounting the root filesystem via NFS (nfsroot) -=============================================== - -Written 1996 by Gero Kuhlmann -Updated 1997 by Martin Mares -Updated 2006 by Nico Schottelius -Updated 2006 by Horms - - - -In order to use a diskless system, such as an X-terminal or printer server -for example, it is necessary for the root filesystem to be present on a -non-disk device. This may be an initramfs (see Documentation/filesystems/ -ramfs-rootfs-initramfs.txt), a ramdisk (see Documentation/initrd.txt) 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, NFS client support needs to be selected as -built-in during configuration. Once this has been selected, the nfsroot -option will become available, which should also be selected. - -In the networking options, kernel level autoconfiguration can be selected, -along with the types of autoconfiguration to support. Selecting all of -DHCP, BOOTP and RARP is safe. - - - - -2.) Kernel command line - ------------------- - -When the kernel has been loaded by a boot loader (see below) it needs to be -told what root fs device to use. And in the case of nfsroot, where to find -both the server and the name of the directory on the server to mount as root. -This can be established using the following 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=[:][,] - - If the `nfsroot' parameter is NOT given on the command line, - the default "/tftpboot/%s" will be used. - - Specifies the IP address of the NFS server. - The default address is determined by the `ip' parameter - (see below). This parameter allows the use of different - servers for IP autoconfiguration and NFS. - - Name of the directory on the server to mount as root. - If there is a "%s" token in the string, it will be - replaced by the ASCII-representation of the client's - IP address. - - Standard NFS options. All options are separated by commas. - The following defaults are used: - port = as given by server portmap daemon - rsize = 4096 - wsize = 4096 - timeo = 7 - retrans = 3 - acregmin = 3 - acregmax = 60 - acdirmin = 30 - acdirmax = 60 - flags = hard, nointr, noposix, cto, ac - - -ip=:::::: - - 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 - autoconfiguration. - - The parameter can appear alone as the value to the `ip' - parameter (without all the ':' characters before). If the value is - "ip=off" or "ip=none", no autoconfiguration will take place, otherwise - autoconfiguration will take place. The most common way to use this - is "ip=dhcp". - - IP address of the client. - - Default: Determined using autoconfiguration. - - 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. - - Only required for for NFS root. That is autoconfiguration - will not be triggered if it is missing and NFS root is not - in operation. - - Default: Determined using autoconfiguration. - The address of the autoconfiguration server is used. - - IP address of a gateway if the server is on a different subnet. - - Default: Determined using autoconfiguration. - - Netmask for local network interface. If unspecified - the netmask is derived from the client IP address assuming - classful addressing. - - Default: Determined using autoconfiguration. - - Name of the client. May be supplied by autoconfiguration, - but its absence will not trigger autoconfiguration. - - Default: Client IP address is used in ASCII notation. - - Name of network device to use. - - Default: If the host only has one device, it is used. - Otherwise the device is determined using - autoconfiguration. This is done by sending - autoconfiguration requests out of all devices, - and using the device that received the first reply. - - Method to use for autoconfiguration. In the case of options - which specify multiple autoconfiguration protocols, - requests are sent using all protocols, and the first one - to reply is used. - - Only autoconfiguration protocols that have been compiled - into the kernel will be used, regardless of the value of - this option. - - off or none: don't use autoconfiguration - (do static IP assignment instead) - on or any: use any protocol available in the kernel - (default) - dhcp: use DHCP - bootp: use BOOTP - rarp: use RARP - both: use both BOOTP and RARP but not DHCP - (old option kept for backwards compatibility) - - Default: any - - - - -3.) Boot Loader - ---------- - -To get the kernel into memory different approaches can be used. -They depend on various facilities being available: - - -3.1) Booting from a floppy using syslinux - - When building kernels, an easy way to create a boot floppy that uses - syslinux is to use the zdisk or bzdisk make targets which use - and bzimage images respectively. Both targets accept the - FDARGS parameter which can be used to set the kernel command line. - - e.g. - make bzdisk FDARGS="root=/dev/nfs" - - Note that the user running this command will need to have - access to the floppy drive device, /dev/fd0 - - For more information on syslinux, including how to create bootdisks - for prebuilt kernels, see http://syslinux.zytor.com/ - - N.B: Previously it was possible to write a kernel directly to - a floppy using dd, configure the boot device using rdev, and - boot using the resulting floppy. Linux no longer supports this - method of booting. - -3.2) Booting from a cdrom using isolinux - - When building kernels, an easy way to create a bootable cdrom that - uses isolinux is to use the isoimage target which uses a bzimage - image. Like zdisk and bzdisk, this target accepts the FDARGS - parameter which can be used to set the kernel command line. - - e.g. - make isoimage FDARGS="root=/dev/nfs" - - The resulting iso image will be arch//boot/image.iso - This can be written to a cdrom using a variety of tools including - cdrecord. - - e.g. - cdrecord dev=ATAPI:1,0,0 arch/i386/boot/image.iso - - For more information on isolinux, including how to create bootdisks - for prebuilt kernels, see http://syslinux.zytor.com/ - -3.2) Using LILO - When using LILO all the necessary command line parameters may be - specified using the 'append=' directive in the LILO configuration - file. - - However, to use the 'root=' directive you also need to create - a dummy root device, which may be removed after LILO is run. - - mknod /dev/boot255 c 0 255 - - For information on configuring LILO, please refer to its documentation. - -3.3) Using GRUB - When using GRUB, kernel parameter are simply appended after the kernel - specification: kernel - -3.4) Using loadlin - loadlin may be used to boot Linux from a DOS command prompt without - requiring a local hard disk to mount as root. This has not been - thoroughly tested by the authors of this document, but in general - it should be possible configure the kernel command line similarly - to the configuration of LILO. - - Please refer to the loadlin documentation for further information. - -3.5) Using a boot ROM - This is probably the most elegant way of booting a diskless client. - With a boot ROM the kernel is loaded using the TFTP protocol. The - authors of this document are not aware of any no commercial boot - ROMs that support booting Linux over the network. However, there - are two free implementations of a boot ROM, netboot-nfs and - etherboot, both of which are available on sunsite.unc.edu, and both - of which contain everything you need to boot a diskless Linux client. - -3.6) Using pxelinux - Pxelinux may be used to boot linux using the PXE boot loader - which is present on many modern network cards. - - When using pxelinux, the kernel image is specified using - "kernel ". The nfsroot parameters - are passed to the kernel by adding them to the "append" line. - It is common to use serial console in conjunction with pxeliunx, - see Documentation/serial-console.txt for more information. - - For more information on isolinux, including how to create bootdisks - for prebuilt kernels, see http://syslinux.zytor.com/ - - - - -4.) Credits - ------- - - The nfsroot code in the kernel and the RARP support have been written - by Gero Kuhlmann . - - The rest of the IP layer autoconfiguration code has been written - by Martin Mares . - - In order to write the initial version of nfsroot I would like to thank - Jens-Uwe Mager for his help. diff --git a/fs/Kconfig b/fs/Kconfig index d7312825592b..c509123bea49 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -1744,10 +1744,10 @@ config ROOT_NFS If you want your Linux box to mount its whole root file system (the one containing the directory /) from some other computer over the net via NFS (presumably because your box doesn't have a hard disk), - say Y. Read for details. It is - likely that in this case, you also want to say Y to "Kernel level IP - autoconfiguration" so that your box can discover its network address - at boot time. + say Y. Read for + details. It is likely that in this case, you also want to say Y to + "Kernel level IP autoconfiguration" so that your box can discover + its network address at boot time. Most people say N here. diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig index 9c7e5ffb223d..4670683b4688 100644 --- a/net/ipv4/Kconfig +++ b/net/ipv4/Kconfig @@ -160,7 +160,7 @@ config IP_PNP_DHCP If unsure, say Y. Note that if you want to use DHCP, a DHCP server must be operating on your network. Read - for details. + for details. config IP_PNP_BOOTP bool "IP: BOOTP support" @@ -175,7 +175,7 @@ config IP_PNP_BOOTP does BOOTP itself, providing all necessary information on the kernel command line, you can say N here. If unsure, say Y. Note that if you want to use BOOTP, a BOOTP server must be operating on your network. - Read for details. + Read for details. config IP_PNP_RARP bool "IP: RARP support" @@ -187,8 +187,8 @@ config IP_PNP_RARP discovered automatically at boot time using the RARP protocol (an older protocol which is being obsoleted by BOOTP and DHCP), say Y here. Note that if you want to use RARP, a RARP server must be - operating on your network. Read for - details. + operating on your network. Read + for details. # not yet ready.. # bool ' IP: ARP support' CONFIG_IP_PNP_ARP diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c index 7c992fbbc2c3..4824fe8996bf 100644 --- a/net/ipv4/ipconfig.c +++ b/net/ipv4/ipconfig.c @@ -1411,7 +1411,7 @@ late_initcall(ip_auto_config); /* * Decode any IP configuration options in the "ip=" or "nfsaddrs=" kernel - * command line parameter. See Documentation/nfsroot.txt. + * command line parameter. See Documentation/filesystems/nfsroot.txt. */ static int __init ic_proto_name(char *name) {