mirror of https://github.com/mkerrisk/man-pages
Use quotes more consistently in formatting macros.
This commit is contained in:
Michael Kerrisk
parent
c8ce4bc62e
commit
c342a49b0f
129
man4/initrd.4
129
man4/initrd.4
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@ -56,11 +56,13 @@ already created, it can be created with the following commands:
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.PP
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Also, support for both "RAM disk" and "Initial RAM disk"
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(e.g.
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.BR CONFIG_BLK_DEV_RAM=y " and " CONFIG_BLK_DEV_INITRD=y )
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.BR CONFIG_BLK_DEV_RAM=y
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and
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.BR CONFIG_BLK_DEV_INITRD=y )
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must be compiled directly into the Linux kernel to use
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.IR /dev/initrd "."
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.IR /dev/initrd .
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When using
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.IR /dev/initrd ", "
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.IR /dev/initrd ,
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the RAM disk driver cannot be loaded as a module.
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.\"
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.\"
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@ -103,10 +105,12 @@ different device.
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.\"
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.SS "Boot-up Operation"
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When booting up with
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.BR initrd ", the system boots as follows:"
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.BR initrd ,
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the system boots as follows:
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.IP 1. 3
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The boot loader loads the kernel program and
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.IR /dev/initrd "'s contents into memory."
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.IR /dev/initrd 's
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contents into memory.
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.IP 2.
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On kernel startup,
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the kernel uncompresses and copies the contents of the device
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@ -114,7 +118,7 @@ the kernel uncompresses and copies the contents of the device
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onto device
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.I /dev/ram0
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and then frees the memory used by
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.IR /dev/initrd "."
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.IR /dev/initrd .
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.IP 3.
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The kernel then read-write mounts device
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.I /dev/ram0
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@ -126,7 +130,9 @@ If the indicated normal root file system is also the initial root file-system
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) then the kernel skips to the last step for the usual boot sequence.
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.IP 5.
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If the executable file
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.IR /linuxrc " is present in the initial root file-system, " /linuxrc
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.IR /linuxrc
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is present in the initial root file-system,
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.I /linuxrc
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is executed with UID 0.
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(The file
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.I /linuxrc
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@ -144,27 +150,38 @@ terminates, the normal root file system is mounted.
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.I /linuxrc
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exits with any file-systems mounted on the initial root
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file-system, then the behavior of the kernel is
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.BR UNSPECIFIED "."
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.BR UNSPECIFIED .
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See the NOTES section for the current kernel behavior.)
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.IP 7.
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If the normal root file has directory
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.IR /initrd ", device"
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.IR /initrd ,
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device
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.I /dev/ram0
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is moved from
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.IR / " to " /initrd "."
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.IR /
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to
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.IR /initrd .
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Otherwise if directory
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.IR /initrd " does not exist device " /dev/ram0 " is unmounted."
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.IR /initrd
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does not exist device
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.I /dev/ram0
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is unmounted.
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(When moved from
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.IR / " to " /initrd ", " /dev/ram0
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.IR /
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to
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.IR /initrd ,
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.I /dev/ram0
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is not unmounted and therefore processes can remain running from
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.IR /dev/ram0 "."
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.IR /dev/ram0 .
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If directory
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.I /initrd
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does not exist on the normal root file-system
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and any processes remain running from
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.IR /dev/ram0 " when " /linuxrc
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.IR /dev/ram0
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when
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.I /linuxrc
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exits, the behavior of the kernel is
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.BR UNSPECIFIED "."
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.BR UNSPECIFIED .
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See the NOTES section for the current kernel behavior.)
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.IP 8.
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The usual boot sequence (e.g. invocation of
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@ -175,11 +192,12 @@ is performed on the normal root file system.
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.\"
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.SS Options
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The following boot loader options when used with
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.BR initrd ", affect the kernel's boot-up operation:"
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.BR initrd ,
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affect the kernel's boot-up operation:
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.TP
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.BI initrd= "filename"
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Specifies the file to load as the contents of
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.IR /dev/initrd "."
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.IR /dev/initrd .
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For
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.B LOADLIN
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this is a command line option.
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@ -209,11 +227,16 @@ is read-only and can be read only one time after system startup.
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.TP
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.BI root= "device-name"
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Specifies the device to be used as the normal root file system.
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.RB "For " LOADLIN
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For
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.B LOADLIN
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this is a command line option.
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.RB "For " LILO " this is a boot time option or
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For
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.B LILO
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this is a boot time option or
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can be used as an option line in the
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.BR LILO " configuration file " /etc/lilo.config "."
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.B LILO
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configuration file
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.IR /etc/lilo.config .
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The device specified by the this option must be a mountable
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device having a suitable root file-system.
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.\"
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@ -228,12 +251,17 @@ or compiled into the kernel file),
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or the boot loader option setting
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is used for the normal root file systems.
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For a NFS-mounted normal root file system, one has to use the
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.BR nfs_root_name " and " nfs_root_addrs
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.B nfs_root_name
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and
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.B nfs_root_addrs
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boot options to give the NFS settings.
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For more information on NFS-mounted root see the kernel documentation file
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.BR nfsroot.txt "."
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.BR nfsroot.txt .
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For more information on setting the root file system also see the
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.BR LILO " and " LOADLIN " documentation."
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.BR LILO
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and
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LOADLIN
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documentation.
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.PP
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It is also possible for the
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.I /linuxrc
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@ -241,24 +269,28 @@ executable to change the normal root device.
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For
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.I /linuxrc
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to change the normal root device,
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.IR /proc " must be mounted."
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.IR /proc
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must be mounted.
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After mounting
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.IR /proc ", " /linuxrc
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.IR /proc ,
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.I /linuxrc
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changes the normal root device by writing into the proc files
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.IR /proc/sys/kernel/real-root-dev ", "
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.IR /proc/sys/kernel/nfs-root-name ", and "
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.IR /proc/sys/kernel/nfs-root-addrs "."
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.IR /proc/sys/kernel/real-root-dev ,
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.IR /proc/sys/kernel/nfs-root-name ,
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and
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.IR /proc/sys/kernel/nfs-root-addrs .
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For a physical root device, the root device is changed by having
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.I /linuxrc
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write the new root file system device number into
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.IR /proc/sys/kernel/real-root-dev "."
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.IR /proc/sys/kernel/real-root-dev .
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For a NFS root file system, the root device is changed by having
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.I /linuxrc
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write the NFS setting into files
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.IR /proc/sys/kernel/nfs-root-name " and "
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.IR /proc/sys/kernel/nfs-root-name
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and
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.I /proc/sys/kernel/nfs-root-addrs
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and then writing 0xff (e.g. the pseudo-NFS-device number) into file
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.IR /proc/sys/kernel/real-root-dev "."
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.IR /proc/sys/kernel/real-root-dev .
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For example, the following shell command line would change
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the normal root device to
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.IR /dev/hdb1 :
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@ -304,8 +336,11 @@ A possible system installation scenario is as follows:
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.IP 1. 3
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The loader program boots from floppy or other media with a minimal kernel
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(e.g. support for
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.IR /dev/ram ", " /dev/initrd ", and the ext2 file-system) and loads "
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.IR /dev/initrd " with a gzipped version of the initial file-system.
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.IR /dev/ram ,
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.IR /dev/initrd ,
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and the ext2 file-system) and loads
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.IR /dev/initrd
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with a gzipped version of the initial file-system.
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.IP 2.
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The executable
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.I /linuxrc
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@ -327,13 +362,15 @@ creates and populates the root file system.
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completed system yet.)
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.IP 5.
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The executable
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.IR /linuxrc " sets " /proc/sys/kernel/real-root-dev,
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.IR /linuxrc
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sets
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.IR /proc/sys/kernel/real-root-dev ,
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unmount
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.IR /proc ", "
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.IR /proc ,
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the normal root file system and any other file
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systems it has mounted, and then terminates.
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.PP
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6. The kernel then mounts the normal root file system.
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.IP 6.
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The kernel then mounts the normal root file system.
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.IP 7.
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Now that the file system is accessible and intact,
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the boot loader can be installed.
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@ -387,21 +424,27 @@ from CD-ROM without the need of any floppies.
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The distribution could also use a
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.B LILO
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boot floppy and then bootstrap a bigger ram disk via
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.IR /dev/initrd " from the CD-ROM."
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.IR /dev/initrd
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from the CD-ROM.
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.\"
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.\"
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.\"
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.SH NOTES
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.IP 1. 3
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With the current kernel, any file systems that remain mounted when
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.IR /dev/ram0 " is moved from " / " to " /initrd
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.I /dev/ram0
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is moved from
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.I /
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to
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.I /initrd
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continue to be accessible.
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However, the
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.I /proc/mounts
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entries are not updated.
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.IP 2.
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With the current kernel, if directory
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.IR /initrd " does not exist, then "
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.I /initrd
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does not exist, then
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.I /dev/ram0
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will
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.B not
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@ -409,10 +452,10 @@ be fully unmounted if
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.I /dev/ram0
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is used by any process or has any file-system mounted on it.
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If
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.IR /dev/ram0 " is
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.IR /dev/ram0
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is
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.B not
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fully unmounted, "
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then
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fully unmounted, then
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.I /dev/ram0
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will remain in memory.
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.IP 3.
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