A virtual machine in Uvmm is configured with a device tree that contains information about the VMs resources, memory layout, virtual CPUs and peripheral devices.

Uvmm_dtg is a tool to generate such a device tree at runtime according to its command line.

Capabilities

dt

The dataspace that the device tree is put into.

Command Line Options

-- prints to stdout. On L4Re, the string given as <file> is interpreted as a named capability which needs to be backed by a sufficiently large Dataspace. On Linux, a file with the given name is created. In both cases, uvmm_dtg will output into the named file.

String value.

-h, --help

Show help.

Flag. True if provided.
--arch <target architecture>

Select the target architecture.

Possible values for <target architecture> are x86, x86_64, arm32, arm64, mips32, mips64
--format <format>

Select the output format.

Possible values for <format> are
- txt: The device tree will be printed as plain text (dts).
- bin: The device tree will be output as binary (dtb).
--mem-base <membase>

Configure the start of the memory distribution. membase can be defined in both decimal and hex notations. uvmm_dtg rounds the given base up to the platforms page size.

This value can be overridden by memory devices with fixed addresses.

Numerical value.
--device <devicename:[Option1,Option2=value,Option3=value,...]>

This configures a device.

To get a list of supported devices, use --device help.

To get help for a specific device, use --device devicename:help.

String value.

Examples

Usage in L4Re

Example lua script for Ned:

-- Create DS holding device tree
local dt = L4.Env.user_factory:create(L4.Proto.Dataspace, 4 * 1024):m("rw");
 
-- Start the generator
L4.default_loader:start(
{
  caps = { dt = dt },
}, "rom/uvmm_dtg dt"):wait();
 
-- Start uvmm
vmm.start_vm
{
  ...
  ext_caps = { dt = dt },
  fdt = "dt",
  ...
}

Please notice the :wait() when starting uvmm_dtg. This makes Ned pause until uvmm_dtg has exited and put the device tree into the dataspace such that Uvmm can commence.