Manifest.md

Hafnium Manifest

Format

The format of the manifest is a simple DeviceTree overlay:

/dts-v1/;
/plugin/;

&{/} {
	hypervisor {
		vm1 {
			debug_name = "name";
		};

		vm2 {
			debug_name = "name";
			kernel_filename = "filename";
			vcpu_count = <N>;
			mem_size = <M>;
		};
		...
	};
};

Note: &{/} is a syntactic sugar expanded by the DTC compiler. Make sure to use the DTC in prebuilts/ as the version packaged with your OS may not support it yet.

Example

The following manifest defines two secondary VMs, the first one with 1MB of memory, 2 CPUs and kernel image called kernel0 (matches filename in Hafnium's ramdisk), while the second one has 2MB of memory, 4 CPUs and a kernel image called kernel1.

/dts-v1/;
/plugin/;

&{/} {
	hypervisor {
		vm1 {
			debug_name = "primary VM";
		};

		vm2 {
			debug_name = "secondary VM 1";
			kernel_filename = "kernel0";
			vcpu_count = <2>;
			mem_size = <0x100000>;
		};

		vm3 {
			debug_name = "secondary VM 2";
			kernel_filename = "kernel1";
			vcpu_count = <4>;
			mem_size = <0x200000>;
		};
	};
};

Compiling

Hafnium expects the manifest as part of the board FDT, i.e. DeviceTree in binary format (DTB).

First, compile the manifest into a DTBO (binary overlay):

prebuilts/linux-x64/dtc/dtc -I dts -O dtb --out-version 17 -o manifest.dtbo <manifest_source_file>

Then overlay it with the DTB of your board:

prebuilts/linux-x64/dtc/fdtoverlay -i <board DTB> -o <output DTB> manifest.dtbo