Crate risc0_build
source ·Expand description
Build RISC Zero zkVM guest code and provide handles to the host side.
In order for the host to execute guest code in the RISC Zero zkVM, the host must be provided a compiled RISC-V ELF file and the corresponding ImageID. This crate contains the functions needed to take zkVM guest code, build a corresponding ELF file and ImageID, and make the ImageID and a path to the ELF file available for the host to use.
Using risc0-build to build guest methods
Using this crate can be a bit delicate, so we encourage you to follow along
in our RISC Zero Rust Starter repository.
In that repository, risc0-build is used in the
methods directory.
Guest methods are embedded for the host to use by calling embed_methods
(or embed_methods_with_options) in a build script.
An example build.rs file would look like
fn main() {
risc0_build::embed_methods();
}This requires including risc0-build as a build dependency. You will also
need add a [package.metadata.risc0] section to your cargo file. In this
section, put a methods field with a list of relative paths containing the
guest code. For example, if your guest code is in the guest directory,
then Cargo.toml might include
[build-dependencies]
risc0-build = "0.12"
[package.metadata.risc0]
methods = ["guest"]
This builds a file methods.rs in your cargo output directory which you
must then include for the host to use. For example, you might make a file
src/lib.rs containing
include!(concat!(env!("OUT_DIR"), "/methods.rs"));
This process will generate an image ID (*_ID) and the contents of an ELF
file (*_ELF). The names will be derived from the name of the ELF
binary, which will be converted to ALL_CAPS to comply with Rust naming
conventions. Thus, if a method binary is named multiply, the image ID
will be named methods::MULTIPLY_ID and the contents of the ELF file will
be named methods::MULTIPLY_ELF. These are included at the beginning
of the host-side code:
use methods::{MULTIPLY_ELF, MULTIPLY_ID};
Structs
embed_methods_with_options.