The boot clock is interesting for tracing purpose as it doesn't stop on device suspend. Exporting it intends to let the nVHE hypervisor for the arm64 architecture to "replicate" that clock and allow event synchronization with the host. Replicating implies to know the current slope. Bug: 229972309 Change-Id: Iefb6ffc433dac82297401f9acdff9758cc1b6a89 Signed-off-by: Vincent Donnefort <vdonnefort@google.com>