Convenient and safe parsing of Multiboot2 Header structures and the
contained header tags. Usable in no_std
environments, such as a
bootloader. An optional builder
feature also allows the construction of
the corresponding structures.
For every Multiboot2 header structure, there is an ABI-compatible rusty type. This enables a zero-copying parsing design while also enabling the creation of these structures via convenient constructors for the corresponding types.
What this library is good for:
- construct a Multiboot2 header at runtime (constructing one at build-time with macros is not done yet, contributions are welcome!)
- write a Multiboot2-bootloader that parses a Multiboot2-header
- understanding Multiboot2 headers better
- analyze Multiboot2 headers at runtime
This library is always no_std
without alloc
. However, the default builder
-
feature requires the alloc
-crate and an #[global_allocator]
to be available.
You need the builder
only if you want to construct new headers at runtime.
For parsing, the feature is not relevant, and you can deactivate it.
# without `builder`-feature (and without `alloc`-crate)
multiboot2-header = { version = "<latest>", default-features = false }
# else (requires `alloc`-crate)
multiboot2-header = "<latest>"
use multiboot2_header::builder::{InformationRequestHeaderTagBuilder, Multiboot2HeaderBuilder};
use multiboot2_header::{HeaderTagFlag, HeaderTagISA, MbiTagType, RelocatableHeaderTag, RelocatableHeaderTagPreference, Multiboot2Header};
/// Small example that creates a Multiboot2 header and parses it afterwards.
fn main() {
// We create a Multiboot2 header during runtime here. A practical example is that your
// program gets the header from a file and parses it afterwards.
let mb2_hdr_bytes = Multiboot2HeaderBuilder::new(HeaderTagISA::I386)
.relocatable_tag(RelocatableHeaderTag::new(
HeaderTagFlag::Required,
0x1337,
0xdeadbeef,
4096,
RelocatableHeaderTagPreference::None,
))
.information_request_tag(
InformationRequestHeaderTagBuilder::new(HeaderTagFlag::Required)
.add_irs(&[MbiTagType::Cmdline, MbiTagType::BootLoaderName]),
)
.build();
// Cast bytes in vector to Multiboot2 information structure
let mb2_hdr = unsafe { Multiboot2Header::from_addr(mb2_hdr_bytes.as_ptr().cast()) };
println!("{:#?}", mb2_hdr);
}
You can use the builder, construct a Multiboot2 header, write it to a file and include it like this:
#[used]
#[no_mangle]
#[link_section = ".text.multiboot2_header"]
static MULTIBOOT2_HDR: [u8; 64] = *include_bytes!("mb2_hdr_dump.bin");
You may need a special linker script to place this symbol in the first 32768 bytes of the ELF. See Multiboot2 specification.
The MSRV is 1.75.0 stable.
See main README file.