Skip to content

Latest commit

 

History

History
207 lines (159 loc) · 16.3 KB

CONFIG.md

File metadata and controls

207 lines (159 loc) · 16.3 KB
Raw

Limine configuration file

Location of the config file

First, Limine considers configurations supplied to it as SMBIOS OEM String entries (Type 11). Such configurations are accepted if the first string of such an entry starts with the prefix of limine:config:. The rest of the string is taken as the config file. If such a configuration is found, no further scanning for config files is done. As such, the boot(): drive is undefined on BIOS, and set to the boot device of Limine on UEFI.

Next, Limine scans for a config file on the boot drive. Every partition on the boot drive is scanned sequentially - first partition first (or, on UEFI, the partition containing the EFI executable of the booted Limine is scanned first), last partition last - for the presence of either a /limine.conf, /limine/limine.conf, /boot/limine.conf, /boot/limine/limine.conf, or a /EFI/BOOT/limine.conf file, in that order.

Once the file is located, Limine will use it as its config file. Other possible candidates in subsequent partitions or directories are ignored.

It is thus imperative that the intended config file is placed in a location that will not be shadowed by another candidate config file.

Structure of the config file

The Limine configuration file is comprised of menu entries and options. Comments begin in '#' and can only be on their own lines.

Menu entries and sub-entries

Menu entries describe entries which the user can select in the boot menu.

A menu entry is opened by a line starting with / followed by a newline-terminated string, that being the title of the entry which the user will see. Any local option that comes after it, and before another menu entry, or the end of the file, will be part of that menu entry.

A menu entry can be a directory, meaning it can hold sub-entries. In order for an entry to become a directory, it needs to have a sub-entry following right after it. (A comment option may be present between the beginning of the directory entry and the beginning of the sub-entry).

A sub-entry is a menu entry started with a number of / greater than 1 prepended to it. Each / represents 1 level deeper down the tree hierarchy of directories and entries.

Directories can be expanded (meaning they will not show up as collapsed in the menu) by default if a + is put between the /s and the beginning of the entry's title.

Options

Options are simple option_name: string... style "assignments". The string can have spaces and other special characters, without requiring quotations. New lines are delimiters. Option names are not case sensitive.

Some options are part of an entry (local), some other options are global. Global options can appear anywhere in the file and are not part of an entry, although usually one would put them at the beginning of the config. Some local options work the same between entries using any protocol, while other local options are specific to a given protocol.

Some options take paths as strings; these are described in the next section.

Global options are:

Miscellaneous:

  • timeout - Specifies the timeout in seconds before the first entry is automatically booted. If set to no, disable automatic boot. If set to 0, boots default entry instantly (see default_entry option).
  • quiet - If set to yes, enable quiet mode, where all screen output except panics and important warnings is suppressed. If timeout is not 0, the timeout still occurs, and pressing any key during the timeout will reveal the menu and disable quiet mode.
  • serial - If set to yes, enable serial I/O for the bootloader.
  • serial_baudrate - If serial is set to yes, this specifies the baudrate to use for serial I/O. Defaults to 9600. BIOS only, ignored with Limine UEFI.
  • default_entry - 1-based entry index of the entry which will be automatically selected at startup. If unspecified, it is 1.
  • remember_last_entry - If set to yes, remember last booted entry. (UEFI only)
  • graphics - If set to no, force CGA text mode for the boot menu, else use a video mode. Ignored with Limine UEFI.
  • wallpaper - Path where to find the file to use as wallpaper. BMP, PNG, and JPEG formats are supported.
  • wallpaper_style - The style which will be used to display the wallpaper image: tiled, centered, or stretched. Default is stretched.
  • backdrop - When the background style is centered, this specifies the colour of the backdrop for parts of the screen not covered by the background image, in RRGGBB format.
  • verbose - If set to yes, print additional information during boot. Defaults to not verbose.
  • randomise_memory - If set to yes, randomise the contents of RAM at bootup in order to find bugs related to non zeroed memory or for security reasons. This option will slow down boot time significantly. For the BIOS port of Limine, this will only randomise memory below 4GiB.
  • randomize_memory - Alias of randomise_memory.
  • hash_mismatch_panic - If set to no, do not panic if there is a hash mismatch for a file, but print a warning instead.

Limine interface control options:

  • interface_resolution - Specify screen resolution to be used by the Limine interface (menu, editor, console...) in the form <width>x<height>. This will only affect the Limine interface, not any booted OS. If not specified, Limine will pick a resolution automatically. If the resolution is not available, Limine will pick another one automatically. Ignored if using text mode.
  • interface_branding - A string that will be displayed on top of the Limine interface.
  • interface_branding_colour - A value between 0 and 7 specifying the colour of the branding string. Default is cyan (6).
  • interface_branding_color - Alias of interface_branding_colour.
  • interface_help_hidden - Hides the help text located at the top of the screen showing the key bindings.

Limine graphical terminal control options:

These are ignored if using text mode.

  • term_font - Path to a font file to be used instead of the default one for the menu and terminal. The font file must be a code page 437 character set comprised of 256 consecutive glyph bitmaps. Each glyph's bitmap must be expressed left to right (1 byte per row), and top to bottom (16 bytes per whole glyph by default; see term_font_size). See e.g. the VGA text mode font collection for fonts.
  • term_font_size - The size of the font in dots, which must correspond to the font file or the display will be garbled. Note that glyphs are always one byte wide, and columns over 8 are empty. Many fonts may be used in both 8- and 9-dot wide variants. Defaults to 8x16. Ignored if term_font not set or if the font fails to load.
  • term_font_scale - Scaling for the font in the x and y directions. 2x2 would display the font in double size, which is useful on high-DPI displays at native resolution. 2x1 only makes the font twice as wide, similar to the VGA 40 column mode. 4x2 might be good for a narrow font on a high resolution display. Values over 8 are disallowed. Default is no scaling, i.e. 1x1.
  • term_font_spacing - Horizontal spacing, in pixels, between glyphs on screen. It is equivalent to setting a font width of <specified width>+<this value>, except this value is preserved even in case font loading fails, and it also applies to the built-in Limine font. Defaults to 1. 0 is allowed.
  • term_palette - Specifies the colour palette used by the terminal (RRGGBB). It is a ; separated array of 8 colours: black, red, green, brown, blue, magenta, cyan, and gray. Ignored if not using a graphical terminal.
  • term_palette_bright - Specifies the bright colour palette used by the terminal (RRGGBB). It is a ; separated array of 8 bright colours: dark gray, bright red, bright green, yellow, bright blue, bright magenta, bright cyan, and white. Ignored if not using a graphical terminal.
  • term_background - Terminal text background colour (TTRRGGBB). TT stands for transparency.
  • term_foreground - Terminal text foreground colour (RRGGBB).
  • term_background_bright - Terminal text background bright colour (RRGGBB).
  • term_foreground_bright - Terminal text foreground bright colour (RRGGBB).
  • term_margin - Set the amount of margin around the terminal.
  • term_margin_gradient - Set the thickness in pixel for the gradient around the terminal.

Editor control options:

  • editor_enabled - If set to no, the editor will not be accessible. Defaults to yes unless a config hash is enrolled.
  • editor_highlighting - If set to no, syntax highlighting in the editor will be disabled. Defaults to yes.
  • editor_validation - If set to no, the editor will not alert you about invalid options or syntax errors. Defaults to yes.

Locally assignable (non protocol specific) options are:

  • comment - An optional comment string that will be displayed by the bootloader on the menu when an entry is selected.
  • protocol - The boot protocol that will be used to boot the kernel. Valid protocols are: linux, limine, multiboot (or multiboot1), multiboot2, efi_chainload, bios_chainload, and chainload_next.
  • cmdline - The command line string to be passed to the kernel/executable. Can be omitted.
  • kernel_cmdline - Alias of cmdline.

Locally assignable (protocol specific) options are:

  • Linux protocol:

    • kernel_path - The path of the kernel.
    • module_path - The path to a module (such as initramfs). This option can be specified multiple times to specify multiple modules.
    • resolution - The resolution to be used. This setting takes the form of <width>x<height>x<bpp>. If the resolution is not available, Limine will pick another one automatically. Omitting <bpp> will default to 32.
    • textmode - If set to yes, prefer text mode. (BIOS only)
    • dtb_path - A device tree blob to pass instead of the one provided by the firmware.

  • Limine protocol:

    • kernel_path - The path of the kernel.
    • module_path - The path to a module. This option can be specified multiple times to specify multiple modules.
    • module_cmdline - A command line to be passed to a module. This option can also be specified multiple times. It applies to the module described by the last module option specified.
    • resolution - The resolution to be used. This setting takes the form of <width>x<height>x<bpp>. If the resolution is not available, Limine will pick another one automatically. Omitting <bpp> will default to 32.
    • kaslr - For relocatable kernels, if set to no, disable kernel address space layout randomisation. KASLR is enabled by default.
    • randomise_hhdm_base - If set to yes, randomise the base address of the higher half direct map. If set to no, do not. By default it is yes if KASLR is supported and enabled, else it is no.
    • randomize_hhdm_base - Alias of randomise_hhdm_base.
    • max_paging_mode, min_paging_mode - Limit the maximum and minimum paging modes to one of the following:
      • x86-64 and aarch64: 4level, 5level.
      • riscv64: sv39, sv48, sv57.
      • loongarch64: 4level.
    • paging_mode - Equivalent to setting both max_paging_mode and min_paging_mode to the same value.
    • dtb_path - A device tree blob to pass instead of the one provided by the firmware.

  • multiboot1 and multiboot2 protocols:

    • kernel_path - The path of the kernel.
    • module_path - The path to a module. This option can be specified multiple times to specify multiple modules.
    • module_string - A string to be passed to a module. This option can also be specified multiple times. It applies to the module described by the last module option specified.
    • resolution - The resolution to be used should the kernel request a graphical framebuffer. This setting takes the form of <width>x<height>x<bpp> and overrides any resolution requested by the kernel. If the resolution is not available, Limine will pick another one automatically. Omitting <bpp> will default to 32.
    • textmode - If set to yes, prefer text mode. (BIOS only)

  • EFI Chainload protocol:

    • image_path - Path of the EFI application to chainload.
    • resolution - The resolution to be used. This setting takes the form of <width>x<height>x<bpp>. If the resolution is not available, Limine will pick another one automatically. Omitting <bpp> will default to 32.

  • BIOS Chainload protocol:

    • drive - The 1-based drive to chainload, if omitted, assume boot drive.
    • partition - The 1-based partition to chainload, if omitted, or set to 0, chainload drive (MBR).
    • mbr_id - Optional. If passed, use an MBR ID (32-bit hex value) to identify the drive containing the volume to chainload. Overrides drive, if present, but does not override partition.
    • gpt_uuid or gpt_guid - Optional. If passed, use the GPT GUID to identify the drive containing the volume to chainload. Overrides drive and mbr_id, if present, but does not override partition.

  • chainload_next protocol:

    • resolution - For UEFI, the resolution to be used. This setting takes the form of <width>x<height>x<bpp>. If the resolution is not available, Limine will pick another one automatically. Omitting <bpp> will default to 32.

Paths

A Limine path is used to locate files in the whole system. It is comprised of a resource, a resource argument, and a path. It takes the form of:

resource(argument):/path

The format for argument changes depending on the resource used.

A resource can be one of the following:

  • boot - If booted off PXE this is an alias of tftp. Else the argument is the 1-based decimal value representing the partition on the boot drive (values of 5+ for MBR logical partitions). If omitted, the partition containing the configuration file on the boot drive is used. For example: boot(2):/... will use partition 2 of the boot drive and boot():/... will use the partition containing the config file on the boot drive.
  • hdd - Hard disk drives. The argument takes the form of drive:partition; for example: hdd(3:1):/... would use hard drive 3, partition 1. Partitions and drives are both 1-based (partition values of 5+ for MBR logical partitions). Omitting the partition is possible; for example: hdd(2:):/.... Omitting the partition will access the entire volume instead of a specific partition (useful for unpartitioned media).
  • odd - Optical disk drives (CDs/DVDs/...). The argument takes the form of drive:partition; for example: odd(3:1):/... would use optical drive 3, partition 1. Partitions and drives are both 1-based (partition values of 5+ for MBR logical partitions). Omitting the partition is possible; for example: odd(2:):/.... Omitting the partition will access the entire volume instead of a specific partition (useful for unpartitioned media, which is often the case for optical media).
  • guid - The argument takes the form of a GUID/UUID, such as guid(736b5698-5ae1-4dff-be2c-ef8f44a61c52):/.... The GUID is that of either a filesystem, when available, or a GPT partition GUID, when using GPT, in a unified namespace.
  • uuid - Alias of guid.
  • fslabel - The argument is the name of the filesystem label of a partition.
  • tftp - The argument is the IP address of the tftp server to load the file from. If the argument is left empty (tftp():/...) the file will be loaded from the server Limine booted from. This resource is only available when booting off PXE.

A path can optionally be suffixed with a blake2b hash for the referenced file, by appending a pound character (#) followed by the blake2b hash. E.g.: boot():/somemodule.tar#ca6914d2...446b470a.

Macros

Macros are strings that can be arbitrarily assigned to represent other strings. For example:

${MY_MACRO}=Some text

Now, whenever ${MY_MACRO} is used in the config file (except for an assignment as above), it will be replaced by the text Some text. For example:

CMDLINE=something before ${MY_MACRO} something after

Macros must always be placed inside ${...} where ... is the arbitrary macro name.

Built-in macros

Limine automatically defines these macros:

  • ARCH - This built-in macro expands to the architecture of the machine. Possible values are: x86-64, ia-32, aarch64, riscv64, loongarch64. In the case of IA-32, BIOS or UEFI, the macro will always expand to x86-64 if the 64-bit extensions are available, else ia-32.
  • FW_TYPE - This built-in macro expands to UEFI if booted using UEFI firmware, or BIOS if booted using legacy x86 BIOS.