Crate vm_fdt

source ·
Expand description

This crate provides the ability to manipulate Flattened Devicetree blobs.

Example

In the following example we create an FDT blob with a root node, and 2 children nodes. More details about this example are available in the readme.

use vm_fdt::{Error, FdtWriter};

fn create_fdt() -> Result<Vec<u8>, Error> {
    let mut fdt = FdtWriter::new()?;

    let root_node = fdt.begin_node("root")?;
    fdt.property_string("compatible", "linux,dummy-virt")?;
    fdt.property_u32("#address-cells", 0x2)?;
    fdt.property_u32("#size-cells", 0x2)?;

    let chosen_node = fdt.begin_node("chosen")?;
    fdt.property_u32("linux,pci-probe-only", 1)?;
    fdt.property_string("bootargs", "panic=-1 console=hvc0")?;
    fdt.end_node(chosen_node)?;

    let memory_node = fdt.begin_node("memory")?;
    fdt.property_string("device_type", "memory")?;
    fdt.end_node(memory_node)?;

    fdt.end_node(root_node)?;

    fdt.finish()
}

By default the FDT does not have any memory reservations. If the user needs to add memory reservations as well, then a different constructor can be used as follows:

use vm_fdt::{Error, FdtReserveEntry, FdtWriter};

fn create_fdt() -> Result<Vec<u8>, Error> {
    let mut fdt = FdtWriter::new_with_mem_reserv(&[
        FdtReserveEntry::new(0x12345678AABBCCDD, 0x1234).unwrap(),
        FdtReserveEntry::new(0x1020304050607080, 0x5678).unwrap(),
    ])?;
    let root_node = fdt.begin_node("root")?;
    // ... add other nodes & properties
    fdt.end_node(root_node)?;

    fdt.finish()
}

The phandle property should be set using FdtWriter::property_phandle, so that the value is checked for uniqueness within the devicetree.

use vm_fdt::{Error, FdtWriter};

fn create_fdt() -> Result<Vec<u8>, Error> {
    let mut fdt = FdtWriter::new()?;

    let root_node = fdt.begin_node("root")?;
    fdt.property_phandle(1)?;

    fdt.end_node(root_node)?;

    fdt.finish()
}

Structs

  • FdtReserveEntry
    Reserved physical memory region.
  • FdtWriter
    Interface for writing a Flattened Devicetree (FDT) and emitting a Devicetree Blob (DTB).
  • FdtWriterNode
    Handle to an open node created by FdtWriter::begin_node.

Enums

  • Error
    Errors associated with creating the Flattened Device Tree.

Type Aliases