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This port will stop execution on the CPU when raised. When lowered, it will allow execution to reset the state of the CPU and allow execution to resume. The state could theoretically be reset when the reset state starts, but then it wouldn't reflect the most up to date condition of the CPU when resuming. For instance, if a reset vector was set somehow, that wouldn't be updated if it was changed while reset was asserted. The tradeoff is that the state won't look like it will when execution resumes while reset is held (to GDB for instance), but that seems like a more obvious and less common sort of problem. This signal is managed by the BaseCPU itself, but is backed by a virtual method which can be overridden by other CPU types which may not work the same way or have the same components. For instance, a fast model CPU could toggle reset lines on the underlying model and let it handle resetting all the state. The fast models in particular already have a generic reset line with the same name, but they have it at the level of the fast model which may have multiple cores within it, each represented by a gem5 CPU. It isn't implemented here, but there could be some sort of cooperation between these signals where the reset at the core level is considered an "or" of the cluster level reset and the individual core level resets. At least in the A76 model, there are resets for each individual core within the cluster as well, which the generic reset toggles. Another option would be to get rid of the whole cluster reset pin, and make the user gang the resets for each of the cores together to whatever reset signal they're using. That's effectively what the cluster level reset is doing, but within the C++ of the model wrapper instead of in the python config. Change-Id: Ie6b4769298ea224ec5dc88360cbb52ee8fbbf69c Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/67574 Tested-by: kokoro <noreply+kokoro@google.com> Reviewed-by: Roger Chang <rogerycchang@google.com> Maintainer: Gabe Black <gabeblack@google.com> Reviewed-by: Yu-hsin Wang <yuhsingw@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.