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Limine Unit

The limine.pas file contains the types and constants described in the Limine Protocol.

The limine.inc file contains the requests which are enabled using define directives. Why?

How do I add the requests to a specific section?

FreePascal does not provide a way to specify section names. Exported symbols use the _limine_request_ prefix allowing the linker script to target any that are enabled.

Example linker script section:

.limine_requests : {
    KEEP(*(.data.*_limine_request_*))
} :limine_requests

Enabling C-style macros

To set specific Limine request values you will need to enable C-style macros:

{$macro on}
{$define LIMINE_<...> := value}
{$macro off}

Examples:

Set a specific base revision:

{$macro on}
{$define LIMINE_BASE_REVISION := 4}
{$macro off}
{$I limine.inc}

Set the entry point:

{$macro on}
{$define LIMINE_ENTRY_POINT := @procedure_name}
{$macro off}
{$define LIMINE_REQUEST_ENTRY_POINT}
{$I limine.inc}

Add internal modules:

{$macro on}
{$define LIMINE_MODULE_COUNT := <count of internal module pointers>}
{$define LIMINE_MODULE_ARRAY := @array_of_internal_module_pointers}
{$macro off}
{$define LIMINE_REQUEST_MODULE}
{$I limine.inc}

Set multiprocessor flags:

{$macro on}
{$define LIMINE_MULTIPROCESSOR_FLAGS := LIMINE_MULTIPROCESSOR_REQUEST_X86_64_X2APIC}
{$macro off}
{$define LIMINE_REQUEST_MULTIPROCESSOR}
{$I limine.inc}

Set paging mode:

{$macro on}
{$define LIMINE_PAGING_MODE_REVISION := 1}
{$define LIMINE_PAGING_MODE := LIMINE_PAGING_MODE_X86_64_DEFAULT}
{$define LIMINE_PAGING_MODE_MIN := LIMINE_PAGING_MODE_X86_64_4LVL}
{$define LIMINE_PAGING_MODE_MAX := LIMINE_PAGING_MODE_X86_64_5LVL}
{$macro off}
{$define LIMINE_REQUEST_PAGING_MODE}
{$I limine.inc}

Set stack size:

{$macro on}
{$define LIMINE_STACK_SIZE := <size in bytes>}
{$macro off}
{$define LIMINE_REQUEST_STACK_SIZE}
{$I limine.inc}

Request specific features

Define the request macros prior to including limine.inc to request features:

{$define LIMINE_REQUEST_BOOTLOADER_INFO}
{$define LIMINE_REQUEST_BOOTLOADER_PERFORMANCE}
{$define LIMINE_REQUEST_DATE_AT_BOOT}
{$define LIMINE_REQUEST_DEVICE_TREE_BLOB}
{$define LIMINE_REQUEST_EFI_MEMORY_MAP}
{$define LIMINE_REQUEST_EFI_SYSTEM_TABLE}
{$define LIMINE_REQUEST_ENTRY_POINT}
{$define LIMINE_REQUEST_EXECUTABLE_ADDRESS}
{$define LIMINE_REQUEST_EXECUTABLE_CMDLINE}
{$define LIMINE_REQUEST_EXECUTABLE_FILE}
{$define LIMINE_REQUEST_FIRMWARE_TYPE}
{$define LIMINE_REQUEST_FLANTERM_FB_INIT_PARAMS}
{$define LIMINE_REQUEST_FRAMEBUFFER}
{$define LIMINE_REQUEST_HHDM}
{$define LIMINE_REQUEST_KEEP_IOMMU}
{$define LIMINE_REQUEST_MEMORY_MAP}
{$define LIMINE_REQUEST_MODULE}
{$define LIMINE_REQUEST_MULTIPROCESSOR}
{$define LIMINE_REQUEST_PAGING_MODE}
{$define LIMINE_REQUEST_RISCV_BSP_HARTID}
{$define LIMINE_REQUEST_RSDP}
{$define LIMINE_REQUEST_SMBIOS}
{$define LIMINE_REQUEST_STACK_SIZE}

Accessing the requests

Available external names for requests:

  • _limine_request_bootloader_info
  • _limine_request_bootloader_performance
  • _limine_request_date_at_boot
  • _limine_request_device_tree_blob
  • _limine_request_efi_memory_map
  • _limine_request_efi_system_table
  • _limine_request_entry_point
  • _limine_request_executable_address
  • _limine_request_executable_cmdline
  • _limine_request_executable_file
  • _limine_request_firmware_type
  • _limine_request_flanterm_fb_init_params
  • _limine_request_framebuffer
  • _limine_request_hhdm
  • _limine_request_keep_iommu
  • _limine_request_memory_map
  • _limine_request_module
  • _limine_request_multiprocessor
  • _limine_request_paging_mode
  • _limine_request_riscv_bsp_hartid
  • _limine_request_rsdp
  • _limine_request_smbios
  • _limine_request_stack_size

Corresponding types for requests:

  • TLimineBootloaderInfoRequest
  • TLimineBootloaderPerformanceRequest
  • TLimineDateAtBootRequest
  • TLimineDeviceTreeBlobRequest
  • TLimineEfiMemoryMapRequest
  • TLimineEfiSystemTableRequest
  • TLimineEntryPointRequest
  • TLimineExecutableAddressRequest
  • TLimineExecutableCmdLineRequest
  • TLimineExecutableFileRequest
  • TLimineFirmwareTypeRequest
  • TLimineFlantermFbInitParamsRequest
  • TLimineFramebufferRequest
  • TLimineHhdmRequest
  • TLimineKeepIommuRequest
  • TLimineMemoryMapRequest
  • TLimineModuleRequest
  • TLimineMultiprocessorRequest
  • TLiminePagingModeRequest
  • TLimineRiscvBspHartIdRequest
  • TLimineRsdpRequest
  • TLimineSmbiosRequest
  • TLimineStackSizeRequest

Example definition for Framebuffer request:

var
  Framebuffer: TLimineFramebufferRequest; external name '_limine_request_framebuffer';

Why is limine include necessary?

FreePascal does not support parameterized C-style macros.

Assigning values to records at compile-time is also limited. Static initialization of records requires literal values.

This is possible:

const
  FramebufferRequest: TLimineFramebufferRequest = (
    Id: (
      QWord($C7B1DD30DF4C8B88),
      QWord($0A82E883A194F07B),
      QWord($9D5827DCD881DD75),
      QWord($A3148604F6FAB11B)
    );
    Revision: 0;
    Response: nil;
  ); export name '_limine_request_framebuffer';

While this is not:

const
  FramebufferRequest: TLimineFramebufferRequest = (
    Id: LIMINE_FRAMEBUFFER_REQUEST_ID;
    Revision: 0;
    Response: nil;
  ); export name '_limine_request_framebuffer';

FreePascal does support basic C-style macros for assigning values.

{$macro on}
{$define LIMINE_BASE_REVISION := 4}
{$macro off}

The C-style macros allow this to work:

const
{$macro on}
  FramebufferRequest: TLimineFramebufferRequest = (
    Id: LIMINE_FRAMEBUFFER_REQUEST_ID;
    Revision: 0;
    Response: nil;
  ); export name '_limine_request_framebuffer';
{$macro off}

It still requires limine.inc to be included, but the requests can be explicitly defined.

Using these macros with limine.inc was the most convenient way I found to make this work. It may change if I find a better alternative.