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.
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>; }; }; };
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