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9398a495eb
Add loader.exit(status). While one can get alomst this behavior with
loader.perform("quit"), quit doesn't allow a value to be returned to the
firmware. The interpretation of 'status' is firmware specific. This can
be used when autobooting doesn't work in scripts, for example, to allow
the firmware to try something else...
Sponsored by: Netflix
Reviewed by: kevans
Differential Revision: https://reviews.freebsd.org/D44094
197 lines
4.4 KiB
Groff
197 lines
4.4 KiB
Groff
.\"
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.\" Copyright (c) 2024 Netflix, Inc.
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.\"
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.\" SPDX-License-Identifier: BSD-2-Clause
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.\"
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.Dd February 6, 2024
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.Dt LOADER.LUA 8
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.Os
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.Sh NAME
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.Nm loader.lua
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.Nd Fx Lua loader module
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.Sh DESCRIPTION
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The built-in Lua bindings for the
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.Fx
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boot loaders using the Lua interpreter
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are available via the
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.Ic loader
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table.
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.Pp
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The
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.Ic loader
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table is always available in Lua scripts.
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There is no need to require it like other loader-specific modules.
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.Ss Exported Variables
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The following variables are provided by the Lua interpreter in the
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.Nm loader
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table:
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.Bl -tag -width machine_arch
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.It Ic machine
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The target's
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.Va hw.machine
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.Xr sysctl 8
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value.
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.It Ic machine_arch
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The target's
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.Va hw.machine_arch
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.Xr sysctl 8
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value.
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Some boot loaders are 32-bit applications that then load a 64-bit
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kernel.
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In these cases,
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.Ic machine_arch
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represents the 32-bit architecture, not the 64-bit architecture.
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.It Ic lua_path
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The current lua loading path.
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.It Ic version
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The version of the boot program.
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.El
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.Ss Exported Functions
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The following functions are exported in the
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.Nm loader
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table.
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.Bl -tag -width term_putimage
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.It Fn delay usec
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Delay for
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.Va usec
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microseconds.
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.It Fn command_error
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Returns the error string from the last command to fail.
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.It Fn command argc argv
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Like
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.Fn perform
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but the arguments are already parsed onto the stack.
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.It Fn exit status
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Exit the boot loader back to the firmware with a status of
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.Va status .
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The interpretation of this value is firmware specific.
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.It Fn interpret str
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Execute the loader builtin command
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.Va str
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as if it were typed by the user.
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This will first try to execute
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.Va str
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as Lua.
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If that fails, it will attempt to execute it as a cli command,
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including those defined by the
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.Xr cli.lua 8
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mechanism.
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If that fails, it will attempt to execute it as a builtin command
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and return the same values as
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.Fn perform .
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.It Fn parse str
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Parses the command
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.Va str
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into its words and return those words on the stack.
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.It Fn getenv name
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Obtains the value of the environment variable
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.Va name .
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.It Fn has_command cmd
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returns
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.Va true
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if
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.Va commmand
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is present in the interpreter as a builtin.
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Otherwise it returns
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.Va nil
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and an error string.
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It does not check the
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.Dq cli
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table to see if a user defined command has been created.
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.It Fn has_feature feature
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returns
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.Va true
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if the
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.Va feature
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is enabled.
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Otherwise it returns
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.Va nil
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and an error string.
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.It Fn perform str
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Execute the loader builtin command
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.Va str .
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Returns the result of the command, one of the following values:
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.Bl -tag -width loader -offset indent
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.It loader.CMD_OK
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The command completed successfully.
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.It loader.CMD_WARN
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The command was successful, but the user stopped its output
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prematurely.
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.It loader.CMD_ERROR
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The command did not complete successfully.
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Use
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.Va command_error
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to retrieve the error.
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.It loader.CMD_CRIT
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The command returned a critical error that was already printed.
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.It loader.CMD_FATAL
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The command determined continuation was not possible
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and the loader panicked.
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In practice, though,
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.Fn panic
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does not return.
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.El
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.It Fn printc str
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Outputs the string using the loader's
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.Fn putchar
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function.
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This function is also available globally as
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.Fn printc .
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.It Fn setenv name value
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Insert or reset the environment variable
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.Va name
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into the loader's environment list.
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If no environment variable with this name exists, one is created.
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If one exists, its value is replaced.
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.It Fn time
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Returns the loader's notion of time, in seconds since 1970.
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The value of loader's notion varies somewhat between different loading
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environments.
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.It Fn unsetenv name
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Removes the environment variable
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.Va name
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from the loader's environment list.
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.El
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.Ss Compatibility
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The functions
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.Fn fb_bezier ,
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.Fn fb_drawrect ,
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.Fn fb_line ,
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.Fn fb_putimage ,
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.Fn fb_set_pixel ,
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.Fn term_drawrect ,
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and
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.Fn term_putimage
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have moved to the
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.Ic gfx
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table.
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They remain in the
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.Ic loader
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table for a transition period and are documented in
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.Xr gfx.lua 8 .
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.Ss Default File
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In addition, the Lua interpreters start with the file
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.Pa /boot/lua/loader.lua
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when they start to boot the system.
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The default one will fixup the screen, load the configuration files, check for a
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password, and then load the menu or load the kernel file and then return.
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If autoboot is enabled, the loaded files will boot.
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.Sh SEE ALSO
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.Xr loader.conf 5 ,
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.Xr core.lua 8 ,
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.Xr gfx.lua 8 ,
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.Xr loader 8 ,
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.Xr sysctl 8
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.Sh AUTHORS
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The
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.Nm
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man page was written by
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.An Warner Losh Aq Mt imp@FreeBSD.org .
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.Sh BUGS
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.Fn command
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and
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.Fn perform
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should return a tuple when there's
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.Va CMD_ERROR
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or worse.
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