Module fdt 

Device Tree (FDT) parsing Device Tree (FDT) parsing for the custom boot protocol.

Parses the Flattened Device Tree to extract boot information:

• Memory map
• Framebuffer
• ACPI RSDP (via EFI System Table)
• Boot command line
• HHDM offset (derived from memory map)

FDT format

The DTB is a binary blob with big-endian fields. Structure tokens:

• 0x1 = FDT_BEGIN_NODE
• 0x2 = FDT_END_NODE
• 0x3 = FDT_PROP
• 0x4 = FDT_NOP
• 0x9 = FDT_END

Cell sizes

The root node defines #address-cells and #size-cells which determine how many 32-bit cells are used for addresses and sizes in reg properties. Default on most platforms: #address-cells=2, #size-cells=2 (8 bytes each).

Structs

FdtHeader 🔒

Constants

DEFAULT_HHDM_OFFSET 🔒

Default HHDM offset for x86_64 (4 GiB). Used when DTB doesn’t specify one.

MAX_CSTRING_LEN 🔒

Maximum string length for FDT strings

MAX_DTB_MEMORY_REGIONS 🔒

Maximum number of memory regions supported from DTB

Statics

DTB_MEMORY_MAP 🔒

Static storage for memory map parsed from DTB.

Functions

build_kernel_args_from_dtb^⚠

Parse the Flattened Device Tree and build a KernelArgs structure.

derive_hhdm_offset 🔒

Derive HHDM offset from the memory map.

find_rsdp_from_efi_systab 🔒 ^⚠

Find RSDP from EFI System Table.

parse_chosen_node 🔒 ^⚠

Parse /chosen node for bootargs, initrd, stdout-path, uefi-systab.

parse_fdt_header 🔒 ^⚠

parse_framebuffer 🔒 ^⚠

Parse framebuffer information from DTB.

parse_memory_nodes 🔒 ^⚠

Parse /memory nodes to build the memory map.

parse_root_properties 🔒 ^⚠

Parse root node properties to extract #address-cells and #size-cells.

read_be32 🔒 ^⚠

Read a big-endian 32-bit value.

read_be64 🔒 ^⚠

Read a big-endian 64-bit value.

read_be_int 🔒 ^⚠

Read a big-endian integer of num_bytes bytes (1–8).

read_cstring 🔒 ^⚠

Read a null-terminated string from memory.

read_prop_u64 🔒 ^⚠

Read a property value as u64 (32 or 64 bit depending on prop_len).

read_reg_property 🔒 ^⚠

Read a reg property value using the correct cell sizes.