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Make this part of the Functional protocol, since it should always return immediately, can be shared by the atomic and timing protocols, and thematically fits with that protocol. The default implementation on the receiving end just ignores the request and leaves the back door pointer set to null, effectively making back doors default "off" which matches their behavior in the atomic protocol. This mechamism helps fix a bug in the TLM gem5 bridges which need to translate to/from the DMI and back door mechanisms, where there can be an explicit request for a back door which does not have a transaction associated with it. It is also necessary for bridging DMI requests in timing mode, since the DMI requests must be instant, and the timing protocol does not send/receive packets instantly. Change-Id: I905f13b9bc83c3fa7877b05ce932e17c308125e2 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/65752 Tested-by: kokoro <noreply+kokoro@google.com> Reviewed-by: Jason Lowe-Power <power.jg@gmail.com> Maintainer: Gabe Black <gabeblack@google.com>
This is the gem5 simulator. The main website can be found at http://www.gem5.org A good starting point is http://www.gem5.org/about, and for more information about building the simulator and getting started please see http://www.gem5.org/documentation and http://www.gem5.org/documentation/learning_gem5/introduction. To build gem5, you will need the following software: g++ or clang, Python (gem5 links in the Python interpreter), SCons, zlib, m4, and lastly protobuf if you want trace capture and playback support. Please see http://www.gem5.org/documentation/general_docs/building for more details concerning the minimum versions of these tools. Once you have all dependencies resolved, type 'scons build/<CONFIG>/gem5.opt' where CONFIG is one of the options in build_opts like ARM, NULL, MIPS, POWER, SPARC, X86, Garnet_standalone, etc. This will build an optimized version of the gem5 binary (gem5.opt) with the the specified configuration. See http://www.gem5.org/documentation/general_docs/building for more details and options. The main source tree includes these subdirectories: - build_opts: pre-made default configurations for gem5 - build_tools: tools used internally by gem5's build process. - configs: example simulation configuration scripts - ext: less-common external packages needed to build gem5 - include: include files for use in other programs - site_scons: modular components of the build system - src: source code of the gem5 simulator - system: source for some optional system software for simulated systems - tests: regression tests - util: useful utility programs and files To run full-system simulations, you may need compiled system firmware, kernel binaries and one or more disk images, depending on gem5's configuration and what type of workload you're trying to run. Many of those resources can be downloaded from http://resources.gem5.org, and/or from the git repository here: https://gem5.googlesource.com/public/gem5-resources/ If you have questions, please send mail to gem5-users@gem5.org Enjoy using gem5 and please share your modifications and extensions.