The tpm_tool is a development only tool intended to test and diagnose issues with Trusted Platform Module or CR50 devices. It works by launching itself inside the /core/ffx-laboratory collection and attempting to connect to to the first available fuchsia.tpm.TpmDevice in the /dev/class/tpm/ directory.
This tool is still very much a work in progress that will be added to as the TPM stack is built for Fuchsia. This is intended for non-production enviroments only mostly to assist in the development of the TPM stack.
If you are wanting to test the tool in an emulated environment first setup your build to utilize x64 which will bring in the tpm-lpc driver.
fx set core.x64 --with //src/security/tools/tpm_tool
Next you will want to setup swtpm setup to passthrough to QEMU. This will launch an emulated TPM that will be accessible via the swtpm-sock.
mkdir /tmp/emulated_tpm swtpm socket --tpmstate dir=/tmp/emulated_tpm --ctrl type=unixio,path=/tmp/emulated_tpm/swtpm-sock --log level=20 --tpm2
Then you will want to setup QEMU to passthrough the swtpm-sock into the guest fuchsia image. This will present itself as a LPC device that the tpm-lpc driver can connect to.
fx qemu -N -- -chardev socket,id=chrtpm,path=/tmp/emulated_tpm/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0 ~
Next you will want to make sure you are serving package for the device:
fx serve
Finally you can run tpm_tool with the following command:
ffx component run /core/ffx-laboratory:tpm fuchsia-pkg://fuchsia.com/tpm_tool#meta/tpm-tool.cm --recreate
You should be able to search for results by running:
fx log | grep tpm_tool