systemc: define control extension

There are some flags in gem5 Packet class to specifying the control
signals, like priv bit, secure bit, etc. For now we don't have the
corresponding way to bridge the information in gem5 and SystemC. The
control extension would be responsible for control signals.

Change-Id: I35ba8610210e0750917a78fa0adb321991968f6a
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/59649
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Reviewed-by: Gabe Black <gabe.black@gmail.com>
2 files changed