user.tex

linux 的引导程序源码The Microsoft&reg Windows&reg Software Development Kit (SDK) provides the documentation

\raw{reserve=\meta{base},\meta{size},$\ldots$} reserves IO port regions.
This can be used to prevent device drivers from auto-probing addresses
where other devices are located, which get confused by the probing.

\raw{ro} instructs the kernel to mount the root file system read-only.
\raw{rw} mounts it read-write. If neither \raw{ro} nor \raw{rw} is
specified, the setting from the boot image is used.

\raw{no-hlt} avoids executing a \raw{HLT} instructions whenever the system
is idle. \raw{HLT} normally significantly reduces power consumption and
therefore also heat
dissipation of the CPU, but may not work properly with some clone CPUs.
\raw{no387} disables using the hardware FPU even if one is present.

\raw{debug} enables more verbose console logging.

Recent kernels also accept the options \raw{init=\meta{name}} and
\raw{noinitrd}. \raw{init} specifies the name of the \name{init} program
to execute. Therefore, if single mode cannot be entered because \name{init}
is mis-configured, one may still be able to reach a shell using
\verb"init=/bin/sh". \raw{noinitrd} disables automatic loading of the initial
RAM disk. Instead, its content is then available on \path{/dev/initrd}.

\raw{vga=\meta{mode}} alters the VGA mode set at startup. The values
\raw{normal}, \raw{extended}, \raw{ask} or a decimal number are
recognized. (See also page \pageref{vga}.)

\raw{kbd=\meta{code},$\ldots$} preloads a sequence of keystrokes in the
BIOS keyboard buffer. The keystrokes have to be entered as 16 bit hexadecimal
numbers, with the upper byte containing the scan code and the lower byte
containing the ASCII code. Note that most programs only use the ASCII
code, so the scan code can frequently be omitted. Scan code tables can be
found in many books on PC hardware. Note that scan codes depend on the
keyboard layout.

Finally, \raw{lock} stores the current command-line as the default
command-line, so that \LILO\ boots the same image with the same options
(including \raw{lock}) when invoked the next time.


\subsubsection{Device-specific options}

There is also a plethora of options to specify certain characteristics
(e.g. IO and memory addresses) of devices. Some common ones are
\raw{ether}, \raw{floppy}, \raw{hd}, \raw{bmouse}, and \raw{sound}.
The usage of these options is \raw{\meta{option}=\meta{number},$\ldots$}.
Please consult the corresponding FAQs and HOWTOs for details. For an overview
of all available options, consult the file \path{init/main.c} in the kernel
source tree.


\subsubsection{Other options}

Options of the type \raw{\meta{variable}=\meta{value}} which are neither
standard options nor device-specific options,
cause the respective variables to be set in the environment passed to
\name{init}. The case of the variable name is preserved, i.e. it isn't
automatically converted to upper case.

Note that environment variables passed to \name{init} are typically
available in system initialization scripts (e.g. \path{/etc/rc.local}),
but they're not visible from ordinary login sessions, because the \name{login}
program removes them from the user's environment.


\subsubsection{Repeating options}

The effect of repeating boot command-line options depends on the options.%
\footnote{Options are frequently repeated when a string defined with
\craw{append} or \craw{literal} is prepended to the parameters typed in by
the user. Also, \LILO\ implicitly prepends the options \raw{ramdisk},
\raw{ro}, \raw{root}, or \raw{rw} when \craw{ramdisk}, \craw{read-only},
\craw{read-write}, or \craw{root}, respectively, are set in the configuration
file.
(\raw{lock} and \raw{vga} are handled by a different internal mechanism.)}
There are three possible behaviours:

Options that only enable or disable a certain functionality can be repeated
any number of times. \raw{debug}, \raw{lock}, \raw{no-hlt}, and \raw{no387}
fall into this category.

Other options change a global setting whenever they appear, so only the
value or presence of the last option matters. The antagonists \raw{ro} and
\raw{rw} are such options. Also, \raw{ramdisk}, \raw{root}, and \raw{vga}
work this way. Example: \raw{ro rw} would mount the root file system
read-write.

Finally, when \raw{reserve} and many device-specific options are repeated,
each occurrence has its own meaning, e.g. \raw{hd=$\ldots$ hd=$\ldots$} would
configure two hard disks, and \raw{reserve=0x300,8 reserve=0x5f0,16} would
reserve the ranges 0x300 to 0x307 and 0x5f0 to 0x5ff (which is equivalent to
writing \raw{reserve=0x300,8,0x5f0,16}).


\subsubsection{Implicit options}

\LILO\ always passes the string \raw{BOOT\_IMAGE=\meta{name}} to the
kernel, where \meta{name} is the name by which the kernel is identified
(e.g. the label). This variable can be used in \path{/etc/rc} to select
a different behaviour, depending on the kernel.

When booting automatically, i.e. without human intervention, the word
\raw{auto} is also passed on
the command line. This can be used by \name{init} to suppress interactive
prompts in the boot phase.


\subsection{Boot image selection}
\label{bootsel}

The details of selecting the boot image are somewhat complicated. The
following tables illustrate them. First, if neither \craw{prompt} is
set nor a shift key is being pressed:

$$
\begin{tabular}{cc|cl}
  Externally & Command  & Auto- & Booted image \\
  provided   & line in  & matic & \\
  cmd. line\footnotemark
  & map file\footnotemark
  & boot\footnotemark
  & \\
  \hline
  No  & No  & Yes & Default image \\
  Yes & --- & Yes & Specified by external \\
      &     &     & command line \\
  No  & Yes & Yes & Specified by command line \\
      &     &     & in map file \\
\end{tabular}
\addtocounter{footnote}{-2}
\footnotetext{Externally provided command lines could be used to
  add front-ends to \LILO. They would pass the respective command
  string to LILO, which would then interpret it like keyboard input. This
  feature is currently not used.}
\addtocounter{footnote}{1}
\footnotetext{This command line is set by invoking the map installer
    with the \raw{-R} option, by using the boot command-line option
    \raw{lock}, or if a fallback command line is set (with \craw{fallback}).}
\addtocounter{footnote}{1}
\footnotetext{I.e. the keyword \raw{auto} is added.}
$$

If \craw{prompt} is not set and a shift key is being pressed:
$$
\begin{tabular}{cccc|cl}
  Input   & Empty  & Extern. & Cmd.l.  & Auto- & Booted image \\
  timeout & cmd.l. & cmd.l.  & in map  & matic & \\
          &        &         & file    & boot  & \\
  \hline
  No  & No  & --- & --- & No  & Specified by the user \\
  No  & Yes & --- & --- & No  & Default image \\
  Yes & n/a & --- & --- & Yes & Default image \\
\end{tabular}
$$

Finally, if the configuration variable \craw{prompt} is set:
$$
\begin{tabular}{cccc|cl}
  Input   & Empty  & Extern. & Cmd.l.  & Auto- & Booted image \\
  timeout & cmd.l. & cmd.l.  & in map  & matic & \\
          &        &         & file    & boot  & \\
  \hline
  No  & No  & No  & No  & No  & Specified by the user \\
  No  & Yes & No  & No  & No  & Default image \\
  Yes & n/a & No  & No  & Yes & Default image \\
  n/a & n/a & Yes & --- & Yes & Specified by external \\
      &     &     &     &     & command line \\
  n/a & n/a & No  & Yes & Yes & Specified by command \\
      &     &     &     &     & line in map file \\
\end{tabular}
$$

Note that \LILO\ pauses for the amount of time specified in \craw{delay}
when at the end of a default command line. The automatic boot can then
be interrupted by pressing a modifier key (\key{Shift}, \key{Ctrl}, etc.).

The default image is the first image in the map file or the image specified
with the \craw{default} variable. However,
after an unsuccessful boot attempt, the respective image becomes the
default image.


\newpage
\section{Map installer}

The map installer program \path{/sbin/lilo} updates the boot sector
and creates the map file. If the map installer detects an error, it terminates
immediately and does not touch the boot sector and the map file.

Whenever the map installer updates a boot sector, the original boot
sector is copied
to \path{/boot/boot.\meta{number}}, where \meta{number} is the
hexadecimal device number. If such a file already exists, no backup
copy is made. Similarly, a file \raw{/boot/part.\meta{number}} is
created if \LILO\ modifies the partition table. (See page \pageref{fix-table}.)


\subsection{Command-line options}

The \LILO\ map installer can be invoked in the following ways:


%%beginskip
\def\seealso{See also sections \ref{corropt} and \ref{cfgglo}.}
%%def\\seealso=See also sections \\ref{corropt} and \\ref{cfgglo}.
%%endskip

\subsubsection{Show current installation}
\label{invshow}

The currently mapped files are listed. With \raw{-v}, also many parameters
are shown.

\begin{command}
  /sbin/lilo
    \unit{\[ -C \meta{config\_file} \]}
    \unit{-q}
    \unit{\[ -m \meta{map\_file} \]}
    \unit{\[ -v $\ldots$ \]}
\end{command}

\begin{description}
  \item[\raw{-C \meta{config\_file}}]~\\
    Specifies the configuration file that is used by the map
    installer (see section \ref{config}). If \raw{-C} is omitted,
    \path{/etc/lilo.conf} is used.
  \item[\raw{-m \meta{map\_file}}]~\\
    Specifies an alternate map file. \seealso
  \item[\raw{-q}]~ \\
    Lists the currently mapped files.
  \item[\raw{-v $\ldots$}]~\\
    Increase verbosity. \seealso
\end{description}


\subsubsection{Create or update map}
\label{creupd}

A new map is created for the images described in the configuration file
\path{/etc/lilo.conf} and they are registered in the boot sector.

\begin{command}
  /sbin/lilo
    \unit{\[ -C \meta{config\_file} \]}
    \unit{\[ -b \meta{boot\_device} \]}
    \unit{\[ -c \]}
    \unit{\[ -l \]}
    \unit{\[ -i \meta{boot\_sector} \]}
    \unit{\[ -f \meta{disk\_tab} \]}
    \unit{\[ -m \meta{map\_file} \]}
    \unit{\[ -d \meta{delay\/} \]}
    \unit{\[ -v $\ldots$ \]}
    \unit{\[ -t \]}
    \unit{\[ -s \meta{save\_file} \|}
    \unit{-S \meta{save\_file} \]}
    \unit{\[ -P fix \|}
    \unit{-P ignore \]}
    \unit{\[ -r \meta{root\_dir} \]}
\end{command}

\begin{description}
  \item[\raw{-b \meta{boot\_device}}]~\\
    Specifies the boot device. \seealso
  \item[\raw{-c}]~\\
    Enables map compaction. \seealso
  \item[\raw{-C \meta{config\_file}}]~\\
    Specifies an alternate configuration file. See also section \ref{invshow}.
  \item[\raw{-d \meta{delay}}]~\\
    Sets the delay before \LILO\ boots the default image. Note that the
    delay is specified in \emphasize{tenths} of a second. \seealso
  \item[\raw{-D \meta{name}}]~\\
    Specifies the default image. \seealso
  \item[\raw{-f \meta{disk\_tab}}]~\\
    Specifies a disk parameter table file. \seealso
  \item[\raw{-i \meta{boot\_sector}}]~\\
    Specifies an alternate boot file. \seealso
  \item[\raw{-L}]~\\
    Enables lba32 sector addresses. \seealso
  \item[\raw{-l}]~\\
    Enables linear sector addresses. \seealso
  \item[\raw{-m \meta{map\_file}}]~\\
    Specifies an alternate map file. \seealso
  \item[\raw{-P \meta{mode}}]~\\
    Specifies how invalid partition table entries should be handled. \seealso
  \item[\raw{-r \meta{root\_directory}}]~ \\
    Chroots to the specified directory before doing anything else. This is
    useful when running the map installer while the normal root file system
    is mounted somewhere else, e.g. when recovering from an installation
    failure with a recovery disk. The \raw{-r} option is implied if
    the environment variable \raw{ROOT} is set.\footnote{E.g. if your root
      partition is mounted on \path{/mnt}, you can update the map by simply
      running \raw{ROOT=/mnt /mnt/sbin/lilo}}
    The current directory is changed to the new root directory, so using
    relative paths may not work.
  \item[\raw{-s \meta{save\_file}}]~\\
    Specifies an alternate boot sector save file. \seealso
  \item[\raw{-S \meta{save\_file}}]~\\
    Like \raw{-s}, but overwrites old save files.
  \item[\raw{-t}]~ \\
    Test only. This performs the entire installation procedure except
    replacing the map file, writing the modified boot sector and fixing
    partition tables. This
    can be used in conjunction with the \raw{-v} option to verify that
    \LILO\ will use sane values.
  \item[\raw{-v $\ldots$}]~\\
    Increase verbosity. \seealso
\end{description}


\subsubsection{Change default command line}
\label{invcmd}

Changes \LILO's default command line. See also section \ref{bootsel}.

\begin{command}
  /sbin/lilo
    \unit{\[ -C \meta{config\_file} \]}
    \unit{\[ -m \meta{map\_file} \]}
    \unit{-R \[ \meta{word} $\ldots$ \]}
\end{command}

\begin{description}
  \item[\raw{-C \meta{config\_file}}]~\\
    Specifies an alternate configuration file. See also section \ref{invshow}.
  \item[\raw{-m \meta{map\_file}}]~\\
    Specifies an alternate map file. \seealso
  \item[\raw{-R \meta{word $\ldots$}}]~ \\
    Stores the specified words in the map file. The boot loader uses those
    words as the default command line when booting the next time. That command
    line is removed from the map file by the boot loader by overwriting the
    sector immediately after reading it. The first word has
    to be the name of a boot image. If \raw{-R} is not followed by any words,
    the current default command line in the map file is erased.\footnote{%